# Claude Sonnet 4 > Source: https://aiwiki.ai/wiki/claude_sonnet_4 > Updated: 2026-10-28 > Fact-checked: 2026-11-02 > Categories: AI Models, Anthropic, Large Language Models > License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) - attribute to "AI Wiki (aiwiki.ai)" > Cite as: AI Wiki. "Claude Sonnet 4." aiwiki.ai, 28 Oct 2026. https://aiwiki.ai/wiki/claude_sonnet_4 > From AI Wiki (https://aiwiki.ai), the free encyclopedia of artificial intelligence. Reuse freely with attribution. **Claude Sonnet 4** is a multimodal hybrid-reasoning [large language model](https://aiwiki.ai/wiki/large_language_model) developed by [Anthropic](https://aiwiki.ai/wiki/anthropic) and released on May 22, 2025. It launched simultaneously with [Claude Opus 4](https://aiwiki.ai/wiki/claude_opus_4) at the company's first developer conference, Code with Claude, in San Francisco, and the two models together formed the opening release of the [Claude 4](https://aiwiki.ai/wiki/claude_4) family.[^1][^2] Sonnet 4 is the mid-tier sibling in the family, sitting between the more capable Opus 4 and the smaller Haiku tier (which did not receive a Claude 4 release in May 2025 and shipped much later as [Claude Haiku 4.5](https://aiwiki.ai/wiki/claude_haiku_4_5) in October).[^3]
Claude logo
Claude logo. Source: Wikimedia Commons, Public domain.
The model uses the API identifier `claude-sonnet-4-20250514` (alias `claude-sonnet-4-0`), supports a 200,000-token [context window](https://aiwiki.ai/wiki/context_window) with up to 64,000 output tokens, and was priced at $3 per million input tokens and $15 per million output tokens at launch, the same price point as Anthropic's previous Sonnet generations going back to [Claude 3.5 Sonnet](https://aiwiki.ai/wiki/claude_3_5_sonnet).[^4][^5] It launched under [AI Safety Level 2 (ASL-2)](https://aiwiki.ai/wiki/responsible_scaling_policy) deployment standards, in contrast to Opus 4 which was released under the stricter ASL-3 standard, the first time Anthropic had ever applied that level to a public model.[^6][^7] At launch, Anthropic positioned Sonnet 4 as a balanced workhorse, what the announcement called "a significant upgrade to Claude Sonnet 3.7, delivering superior coding and reasoning while responding more precisely to your instructions."[^1] Where Opus 4 was framed as the world's best coding model, Sonnet 4 was sold on the optimal mix of capability and cost. The model scored 72.7% on [SWE-bench](https://aiwiki.ai/wiki/swe_bench) Verified at launch, which was state of the art for any non-flagship model on that benchmark at the time, and, like Claude 3.5 Sonnet and Claude 3.7 Sonnet before it, was made available to free [claude.ai](https://aiwiki.ai/wiki/claude) users as well as paid subscribers.[^1][^8][^34] Sonnet 4 became the default model in [Claude Code](https://aiwiki.ai/wiki/claude_code) (which moved out of research preview into general availability on the same day), the model powering [GitHub](https://aiwiki.ai/wiki/github)'s new Copilot [coding agent](https://aiwiki.ai/wiki/coding_agent), and a primary option in [Cursor](https://aiwiki.ai/wiki/cursor), [Replit](https://aiwiki.ai/wiki/replit), Vercel v0, and a long list of partner products.[^1] Sonnet 4 served as the standard Sonnet pick on the Claude API, [Amazon Bedrock](https://aiwiki.ai/wiki/amazon_bedrock), and [Google Cloud](https://aiwiki.ai/wiki/google_cloud) [Vertex AI](https://aiwiki.ai/wiki/google_vertex_ai) until it was superseded by [Claude Sonnet 4.5](https://aiwiki.ai/wiki/claude_sonnet_4_5) on September 29, 2025. The model was formally deprecated on April 14, 2026, with Anthropic naming [Claude Sonnet 4.6](https://aiwiki.ai/wiki/claude_sonnet_4_6) as the recommended replacement, and it was retired from the Claude API on June 15, 2026.[^10][^32] ## Specifications | Specification | Value | | --- | --- | | Release date | May 22, 2025 | | Model family | [Claude 4](https://aiwiki.ai/wiki/claude_4) | | Tier | Sonnet (mid-tier) | | Developer | [Anthropic](https://aiwiki.ai/wiki/anthropic) | | API ID (versioned) | `claude-sonnet-4-20250514` | | API alias | `claude-sonnet-4-0` | | AWS Bedrock ID | `anthropic.claude-sonnet-4-20250514-v1:0` | | Google Vertex AI ID | `claude-sonnet-4@20250514` | | Standard [context window](https://aiwiki.ai/wiki/context_window) | 200,000 tokens (~150,000 words) | | Extended [context window](https://aiwiki.ai/wiki/context_window) | 1,000,000 tokens (beta, August 2025 to April 30, 2026) | | Max output tokens | 64,000 tokens | | Extended thinking | Yes (toggleable via API) | | [Interleaved thinking](https://aiwiki.ai/wiki/interleaved_thinking) | Yes (`interleaved-thinking-2025-05-14` beta header) | | Multimodal input | Text and images | | Output modality | Text only | | Training data cutoff | March 2025 | | Reliable knowledge cutoff | January 2025 | | Parameter count | Undisclosed | | Safety classification | ASL-2 (Anthropic Safety Level 2) | | Priority Tier support | Yes | | List price | $3.00 / $15.00 per million input / output tokens | | Successor | [Claude Sonnet 4.5](https://aiwiki.ai/wiki/claude_sonnet_4_5) (September 29, 2025) | | Recommended replacement (at deprecation) | [Claude Sonnet 4.6](https://aiwiki.ai/wiki/claude_sonnet_4_6) (the deprecations page later listed Claude Sonnet 5.5) | | Deprecation date | April 14, 2026 | | Retired (Claude API) | June 15, 2026 | ## How was Claude Sonnet 4 developed? Anthropic was founded in 2021 by former [OpenAI](https://aiwiki.ai/wiki/openai) researchers Dario and [Daniela Amodei](https://aiwiki.ai/wiki/daniela_amodei) and has trained the Claude family of [language model](https://aiwiki.ai/wiki/language_model)s since the original [Claude 1](https://aiwiki.ai/wiki/claude_1) release in March 2023. The [Claude 3](https://aiwiki.ai/wiki/claude_3) family in March 2024 established the three-tier Haiku, Sonnet, Opus naming pattern and Claude 3.5 Sonnet, released in June 2024, became Anthropic's first widely adopted commercial model. The intermediate [Claude 3.7 Sonnet](https://aiwiki.ai/wiki/claude_3_7_sonnet), released in February 2025, introduced the hybrid reasoning approach that Claude 4 inherited and refined: a single model that can answer quickly to easy prompts and switch into a longer [chain-of-thought](https://aiwiki.ai/wiki/chain_of_thought) reasoning pass for harder ones, with the developer optionally toggling [extended thinking](https://aiwiki.ai/wiki/extended_thinking) on or off through the API.[^2][^11] Work on the Claude 4 generation ran in parallel with that 3.x cycle. Anthropic's stated goal for the new family was to push agentic software engineering and long-horizon autonomous work, two areas the company had identified as the highest-value applications for [frontier models](https://aiwiki.ai/wiki/frontier_models). Anthropic led the launch with [SWE-bench Verified](https://aiwiki.ai/wiki/swe-bench_verified) and Terminal-bench results, and said both Claude 4 models were 65% less likely than Sonnet 3.7 to use shortcuts or loopholes on agentic tasks particularly susceptible to them.[^1][^6] Anthropic does not publish parameter counts, training compute totals, or training data composition for Claude models, including Sonnet 4. The publicly documented training recipe for the Claude 4 family combines pretraining on a large mixture of internet text and licensed data, [supervised fine-tuning](https://aiwiki.ai/wiki/supervised_fine-tuning) on curated demonstrations, [Constitutional AI](https://aiwiki.ai/wiki/constitutional_ai) for alignment training, and [reinforcement learning](https://aiwiki.ai/wiki/reinforcement_learning) from human feedback ([RLHF](https://aiwiki.ai/wiki/rlhf)). The training cutoff for Sonnet 4 is March 2025, with a reliable knowledge cutoff of January 2025, the same dates that apply to Opus 4.[^5][^6] The May 2025 launch was timed for Anthropic's first developer conference, Code with Claude, held in San Francisco on May 22, 2025. The event combined the Sonnet 4 and Opus 4 announcements with the general-availability release of Claude Code and a set of new agent-building API capabilities. It was the first time Anthropic had run a developer-only event in the same format that competitors such as OpenAI and [Google](https://aiwiki.ai/wiki/google) had used for years, and the framing emphasized Anthropic's bet on developer-centric distribution rather than a consumer-chatbot crown chase.[^1][^12] ## When was Claude Sonnet 4 released? Claude Sonnet 4 was announced on May 22, 2025 alongside Claude Opus 4 in a joint launch post titled "Introducing Claude 4." The announcement described the two models as "setting new standards for coding, advanced reasoning, and AI agents," with Opus 4 framed as the flagship and Sonnet 4 as the upgrade to Sonnet 3.7 "delivering superior coding and reasoning while responding more precisely to your instructions."[^1] ### Code with Claude The launch was the headline announcement at Code with Claude, Anthropic's first developer conference. Beyond the two models, the event announced the general availability of Claude Code, the company's terminal-first coding agent, including new integrations for [Visual Studio Code](https://aiwiki.ai/wiki/visual_studio_code), JetBrains, and a GitHub Actions workflow that posted Claude responses on pull requests. An accompanying blog post detailed four new agent-building API features that launched the same day.[^1][^13] The four new API capabilities released alongside the Claude 4 family were: a code execution tool that ran Python in a sandboxed environment for computational and data-visualization tasks; an [MCP](https://aiwiki.ai/wiki/model_context_protocol) connector that let developers wire Claude to remote Model Context Protocol servers without writing custom client code; a Files API that let documents be uploaded once and reused across conversations; and an extended one-hour TTL for [prompt caching](https://aiwiki.ai/wiki/prompt_caching), on top of the existing five-minute cache window.[^13] Anthropic also flipped the default behavior of extended thinking in Claude 4 models so that responses now returned a summary of the model's full thinking process, with the full reasoning encrypted and returned in a `signature` field of each `thinking` block. The default `top_p` nucleus-sampling value moved from 0.999 to 0.99 across all models in the same release.[^32] ### Initial availability Both Claude 4 models were made available on the [Anthropic API](https://aiwiki.ai/wiki/anthropic_api), claude.ai, Amazon Bedrock, and Google Cloud Vertex AI on the day of the announcement. On claude.ai, Opus 4 was restricted to Pro, Max, Team, and Enterprise subscribers. Sonnet 4 was made available to those paying tiers and to free users, continuing the practice Anthropic had followed with Claude 3.5 Sonnet and Claude 3.7 Sonnet of offering its newest Sonnet model on the free tier.[^1][^8][^11][^34] Microsoft Foundry support for Claude did not exist at the time of the May 2025 launch. Anthropic and [Microsoft](https://aiwiki.ai/wiki/microsoft) only added Claude to Foundry on November 18, 2025, six months after Sonnet 4 shipped, and that rollout focused on the then-current Sonnet 4.5 and Haiku 4.5 generation rather than the original Sonnet 4 snapshot.[^32] A wide group of partner products began rolling out Sonnet 4 within hours of the announcement. GitHub committed to using Sonnet 4 as the model behind its new Copilot coding agent. Cursor added it as a selectable model, though the "state-of-the-art for coding" endorsement Anthropic quoted from Cursor, like Replit's comment about improved precision, referred to Opus 4. Sourcegraph, [Augment Code](https://aiwiki.ai/wiki/augment_code), Manus, and iGent each posted endorsements of Sonnet 4 that Anthropic quoted in the launch blog.[^1] ## Architecture Anthropic does not disclose the size, depth, or topology of its models, and Claude Sonnet 4 is no exception. Public documentation describes the model as a transformer-based large language model trained with the company's standard pretraining-plus-Constitutional-AI-plus-RLHF pipeline. The model accepts text and image inputs, produces text-only output, and supports multilingual input and output across the same set of languages as earlier Claude generations.[^5] Anthropic has not published details of the tokenizer used by Sonnet 4. Later models changed it: Claude Opus 4.7, released on April 16, 2026, shipped with an updated tokenizer that Anthropic said can map the same input to roughly 1.0 to 1.35 times as many tokens depending on content type.[^33] The context window can store roughly 500 pages of densely formatted text, enough to fit a small repository or a long research paper. The maximum 64,000-token output is twice the 32,000-token output supported by Opus 4, reflecting Sonnet 4's intended role in routine coding and chat workloads where longer single-turn outputs (full files, long refactors) are common.[^5] ### One-million-token context (beta) A later beta extension added a 1,000,000-token context window for Sonnet 4 on the Anthropic API and Amazon Bedrock behind the `context-1m-2025-08-07` header, announced on August 12, 2025. The fivefold increase over the standard window was sold for "large-scale code analysis" of codebases exceeding 75,000 lines, "document synthesis" across collections of legal contracts, research papers, and specifications, and "context-aware agents" that needed to maintain coherence across hundreds of tool calls.[^14][^15] The same beta header arrived on Google Cloud Vertex AI on August 26, 2025, alongside increased rate limits on the Claude API for long-context requests.[^32] Pricing for the extended-context tier was set at $6 per million input tokens and $22.50 per million output tokens for any prompt that exceeded 200,000 tokens, a doubling of the input rate and a 50% increase on output; prompts at or below 200,000 tokens kept the standard $3 / $15 pricing.[^15] Two partners were featured in the announcement post: Bolt.new, whose CEO Eric Simons said Sonnet 4 had been "consistently outperforming other leading models in production" for code generation, and iGent AI, whose CEO Sean Ward described Maestro's multi-day sessions on real-world codebases as "true production-scale engineering" enabled by the expanded window.[^15] The same beta header carried forward to Sonnet 4.5 when that model launched in September 2025, and to [Claude Opus 4.6](https://aiwiki.ai/wiki/claude_opus_4_6) when it shipped in February 2026, before being retired on April 30, 2026 across the Sonnet 4 generation once Sonnet 4.6 and Opus 4.6 had made one-million-token context generally available without a flag and without a long-context surcharge (a change Anthropic landed on March 13, 2026).[^32] After April 30, 2026, requests to `claude-sonnet-4-20250514` exceeding the standard 200,000-token window returned an error, while shorter requests kept working until the model was retired on June 15, 2026.[^32] ## What is hybrid reasoning in Claude Sonnet 4? Claude Sonnet 4 is a hybrid reasoning model, one of the first Anthropic models after Claude 3.7 Sonnet (launched alongside Opus 4) to expose extended thinking as an explicit, toggleable mode rather than a separate dedicated reasoning model in the style of OpenAI's o1 line. In the default mode, Sonnet 4 produces near-instant responses suited to chat, simple coding, and short instruction-following tasks. With extended thinking enabled, the model first generates a visible internal chain of reasoning before its final answer, with the depth of that reasoning controlled by a `budget_tokens` parameter the developer sets per request.[^1][^11] The minimum thinking budget is 1,024 tokens; the budget must be smaller than the request's `max_tokens`, which for Sonnet 4 can be up to 64,000 tokens. Anthropic recommends modest budgets (a few thousand tokens) for routine reasoning gains and large budgets for hard problems such as competition mathematics, multi-step planning, or graduate-level science. The budget is not a hard cap on reasoning; it is a soft target the model is trained to respect, and the actual length of the visible thinking trace can vary.[^16] A second feature, [interleaved thinking](https://aiwiki.ai/wiki/interleaved_thinking), was introduced as a beta header (`interleaved-thinking-2025-05-14`) at the same launch. With interleaved thinking enabled, Sonnet 4 can think between tool calls during a single assistant turn rather than only at the start, letting the model reason about the result of one tool call before deciding which tool to call next. Anthropic positioned the feature as a building block for agent workflows that needed more careful interleaving of thinking and acting; it carried forward into Opus 4, Sonnet 4.5, and the rest of the family.[^16][^32] In standard mode without extended thinking, Sonnet 4 behaves much like a fast non-reasoning model. With extended thinking on at sensible budgets, it climbs into the reasoning-model bracket on benchmarks such as [GPQA Diamond](https://aiwiki.ai/wiki/gpqa_diamond) and [AIME 2025](https://aiwiki.ai/wiki/aime_2025). The hybrid design was intended to remove the need for application developers to choose between a fast model and a slow reasoning model: the same API surface, the same model ID, and the same prompt template can be used for both styles, with one optional parameter switching modes. The same mechanism was later replaced on Opus 4.6 and Opus 4.7 by "adaptive thinking," where the model chooses its own thinking budget; Sonnet 4 itself kept the original `budget_tokens` model.[^1][^16][^32] ## What can Claude Sonnet 4 do? ### Coding and agentic software engineering Coding was the headline capability for Sonnet 4 at launch. The model was trained explicitly for multi-file codebases, agentic edit-test-fix loops, and long-running developer sessions, and the launch announcement led with the SWE-bench Verified score of 72.7%, the state-of-the-art result for any non-flagship model at that point.[^1] On Terminal-bench, a benchmark that scores agents on real terminal tasks, Sonnet 4 scored 35.5% (or 41.3% with parallel [test-time compute](https://aiwiki.ai/wiki/test_time_compute)), close to Opus 4's 43.2% on the same benchmark.[^8][^17] Partner reports at launch added qualitative color. iGent reported that navigation errors in their autonomous multi-feature app development pipeline dropped from 20% to near zero. Sourcegraph called Sonnet 4 "a substantial leap in software development" and said models running on it stayed on track for longer, generating cleaner code. Augment Code reported "higher success rates, more surgical code edits, and more careful work through complex tasks."[^1] Sonnet 4 became the default model in Claude Code when that product moved out of research preview at the same launch. Free claude.ai users got Sonnet 4 access automatically; Claude Code users on the Pro and Max subscription tiers used Sonnet 4 by default for routine coding work, with Opus 4 available for the heaviest reasoning loads. The combination drove rapid adoption: by mid-2025, Anthropic was citing Claude Code as a major revenue driver, with Sonnet 4 the workhorse model behind most sessions.[^2][^12] ### Tool use and parallel tool use Claude Sonnet 4 supports the same tool-use API as the rest of the Claude 4 family. Developers define tools as JSON schemas, the model emits structured tool calls, and the developer's runtime executes them and feeds results back. Sonnet 4 can fire multiple tool calls in parallel within a single assistant turn, allowing agents to issue several search queries or read several files at once rather than serializing them. Parallel tool use was an explicit improvement over earlier Claude generations and was cited at launch as a major contributor to better agent throughput.[^1][^13] The model also supports the Model Context Protocol (MCP), Anthropic's open standard for plugging models into external tools, both directly through the API's tool framework and via the new MCP connector that the Claude API gained at the May 2025 launch. The MCP connector handles connection management, tool discovery, and error handling for remote [MCP server](https://aiwiki.ai/wiki/mcp_server)s, simplifying integration with services like Asana and [Zapier](https://aiwiki.ai/wiki/zapier) without writing custom client code.[^13] File inputs are handled through the new Files API, also released alongside Claude 4. Documents can be uploaded once and referenced across many conversations, eliminating repeated upload overhead for long-running agents that work over the same set of source files.[^13] ### Computer use Sonnet 4 inherits [computer use](https://aiwiki.ai/wiki/computer_use), the capability to operate a desktop or browser through a sequence of screenshot observations and keyboard or mouse actions, that Claude 3.5 Sonnet introduced in October 2024. On OSWorld, the most cited benchmark for general-purpose computer use, Sonnet 4 scored 42.2% at launch. Anthropic's later Sonnet 4.5 comparison listed [Claude Opus 4.1](https://aiwiki.ai/wiki/claude_opus_4_1) (August 2025) at 44.4%, and Sonnet 4.5 reached 61.4% in September 2025, with Anthropic noting that "just four months ago, Sonnet 4 held the lead at 42.2%."[^18][^19] In the May 2025 form, computer use on Sonnet 4 was framed as a beta capability suitable for controlled environments rather than fully autonomous web browsing. The mid-40% OSWorld score reflected a model that could complete short tasks but tended to fail on complex multi-window desktop work, especially on applications with non-standard UI frameworks. Anthropic explicitly recommended human-in-the-loop oversight for production computer-use deployments at this stage.[^18] ### Vision Sonnet 4 accepts images as input and produces text output. The vision pipeline supports document analysis, chart and figure understanding, screenshot interpretation, and [visual question answering](https://aiwiki.ai/wiki/visual_question_answering) in the same multilingual surface as the text pipeline. On MMMU, the multimodal university benchmark, Sonnet 4 scored 74.4% at launch, in the same band as the strongest non-Anthropic models at the time.[^8] ### Multilingual support Sonnet 4 supports the same multilingual input and output as earlier Claude generations. On the multilingual MMLU variant (MMMLU), the model scored 86.5% at launch, with strong individual results in major European languages and competitive (if uneven) results across Arabic, Chinese, Japanese, Korean, and other non-Latin scripts.[^8] ## How does Claude Sonnet 4 perform on benchmarks? The table below brings together the most cited benchmark results for Claude Sonnet 4 at launch (May 2025) and compares them against Opus 4, its predecessor Claude Sonnet 3.7, and Google [Gemini](https://aiwiki.ai/wiki/gemini) 2.5 Pro (Preview), using the figures in the comparison chart of Anthropic's launch announcement (which also listed OpenAI's o3 and GPT-4.1), as transcribed in contemporaneous write-ups.[^1][^8][^9] | Benchmark | Sonnet 4 | Opus 4 | Claude Sonnet 3.7 | Gemini 2.5 Pro (Preview) | | --- | --- | --- | --- | --- | | [SWE-bench](https://aiwiki.ai/wiki/swe_bench) Verified | 72.7% (80.2% parallel) | 72.5% (79.4% parallel) | 62.3% (70.3% parallel) | 63.2% | | Terminal-bench | 35.5% (41.3% parallel) | 43.2% (50.0% parallel) | 35.2% | 25.3% | | [GPQA](https://aiwiki.ai/wiki/gpqa) Diamond | 75.4% (83.8% parallel) | 79.6% (83.3% parallel) | 78.2% | 83.0% | | [AIME](https://aiwiki.ai/wiki/aime) 2025 | 70.5% (85.0% parallel) | 75.5% (90.0% parallel) | 54.8% | 83.0% | | MMMLU (multilingual [MMLU](https://aiwiki.ai/wiki/mmlu)) | 86.5% | 88.8% | 86.1% | n/a | | [MMMU](https://aiwiki.ai/wiki/mmmu) (validation) | 74.4% | 76.5% | 75.0% | 79.6% | | [Tau-bench](https://aiwiki.ai/wiki/tau-bench) Retail | 80.5% | 81.4% | 81.2% | n/a | | Tau-bench Airline | 60.0% | 59.6% | 58.4% | n/a | Notes: GPQA Diamond, AIME 2025, MMMLU, MMMU, and TAU-bench scores for Sonnet 4 and Opus 4 are reported with extended thinking (up to 64K tokens); SWE-bench Verified and Terminal-bench scores are without extended thinking. Figures in parentheses use Anthropic's high-compute setting with parallel test-time compute; for SWE-bench Verified this gave 80.2% for Sonnet 4 and 79.4% for Opus 4. Anthropic did not report HumanEval or OSWorld in the Claude 4 launch chart; its later Sonnet 4.5 announcement gave Sonnet 4 an OSWorld score of 42.2%. Tau-bench Telecom was not part of the launch benchmark set and was added by Anthropic in later releases.[^1][^8][^18] The headline takeaway from the May 2025 numbers was that Sonnet 4 on its own posted SWE-bench Verified essentially even with the flagship Opus 4 (72.7% vs 72.5%), at one-fifth of Opus's per-token cost. On harder reasoning and graduate-level science benchmarks (GPQA Diamond, AIME), Opus 4 retained a clear edge. On vision, the two models were within two percentage points of each other on MMMU. The pattern was widely cited at the time as evidence that the Sonnet tier was the best price-performance choice for routine coding work and that Opus 4 only paid off for the heaviest reasoning workloads.[^8][^9] Claude Sonnet 3.7, Sonnet 4's direct predecessor, trailed by more than ten points on SWE-bench Verified (62.3%) but was roughly even with or slightly ahead of Sonnet 4 on several knowledge and tool-use benchmarks in Anthropic's chart, including GPQA Diamond (78.2%), MMMU (75.0%), and TAU-bench Retail (81.2%). The biggest jump within the Sonnet line was on agentic coding, the area Anthropic had emphasized.[^1] Contemporaneous write-ups such as DataCamp's largely restated Anthropic's reported figures rather than re-running them. DataCamp called Sonnet 4 "a generalist model that's great for most AI use cases and especially strong at coding" and said it was "not as strong as Opus 4 when it comes to complex reasoning or long-term task planning, but for most workflows, it's more than sufficient."[^8] In hindsight, Sonnet 4's launch numbers held up well against its own descendants on coding. Claude Sonnet 4.5 lifted SWE-bench Verified to 77.2% (single run) or 82.0% with parallel high-compute runs four months later, and Claude Sonnet 4.6 reached 79.6% in February 2026 (80.2% with a prompt modification)[^21]; Sonnet 4 remained competitive on routine workloads and below the standard window threshold even as later generations dominated long-context and computer-use benchmarks.[^18][^32] ## How much does Claude Sonnet 4 cost? ### List pricing Claude Sonnet 4 launched at $3 per million input tokens and $15 per million output tokens, the same headline pricing as Sonnet 3.5 (June 2024) and Sonnet 3.7 (February 2025). The price held without change throughout the model's lifecycle, including after the Sonnet 4.5 supersession in September 2025, and remained the standard Sonnet-tier pricing as of the model's deprecation in April 2026.[^1][^5] The full pricing schedule for Sonnet 4 on the Anthropic API is shown below. | Usage type | Price | | --- | --- | | Input tokens (standard) | $3.00 per million | | Output tokens (standard) | $15.00 per million | | [Prompt caching](https://aiwiki.ai/wiki/prompt_caching) (write, 5-minute TTL) | $3.75 per million | | [Prompt caching](https://aiwiki.ai/wiki/prompt_caching) (write, 1-hour TTL) | $6.00 per million | | [Prompt caching](https://aiwiki.ai/wiki/prompt_caching) (read) | $0.30 per million | | Batch API (input) | $1.50 per million | | Batch API (output) | $7.50 per million | | Extended context input (>200K tokens, beta) | $6.00 per million | | Extended context output (>200K tokens, beta) | $22.50 per million | Prompt caching reduced costs by up to 90% for repeated long-context calls, useful in agent workflows that share a large [system prompt](https://aiwiki.ai/wiki/system_prompt) across many turns. The one-hour cache TTL launched as a beta feature alongside Sonnet 4 on May 22, 2025, and moved to general availability on August 13, 2025. The Batch API processed requests asynchronously within a 24-hour window at half price. Both features were available from launch.[^1][^13][^32] ### Platforms Sonnet 4 was available across Anthropic's first-party distribution at launch and remained on every major platform until its deprecation. The table below lists the main delivery channels. | Platform | Available | Notes | | --- | --- | --- | | [Anthropic API](https://aiwiki.ai/wiki/anthropic_api) | Yes | Both versioned ID and `claude-sonnet-4-0` alias | | claude.ai (web, iOS, Android) | Yes | Free, Pro, Max, Team, Enterprise from day one | | [Amazon Bedrock](https://aiwiki.ai/wiki/amazon_bedrock) | Yes | `anthropic.claude-sonnet-4-20250514-v1:0` | | [Google Cloud](https://aiwiki.ai/wiki/google_cloud) [Vertex AI](https://aiwiki.ai/wiki/google_vertex_ai) | Yes | `claude-sonnet-4@20250514`; 1M beta added Aug 26, 2025 | | Microsoft Foundry | No | Foundry only added Claude on November 18, 2025; rollout focused on Sonnet 4.5 onward | | [Claude Code](https://aiwiki.ai/wiki/claude_code) | Yes | Default Sonnet model from May 22, 2025 | | [GitHub Copilot](https://aiwiki.ai/wiki/github_copilot) | Yes | Selectable model; powered the new Copilot [coding agent](https://aiwiki.ai/wiki/coding_agent) | | [Cursor](https://aiwiki.ai/wiki/cursor) | Yes | Selectable model | | [Replit](https://aiwiki.ai/wiki/replit) | Yes | Used in [Replit Agent](https://aiwiki.ai/wiki/replit_agent) tooling | | Vercel v0 | Yes | Selectable model | | [OpenRouter](https://aiwiki.ai/wiki/openrouter) and other API aggregators | Yes | Routed to [Anthropic API](https://aiwiki.ai/wiki/anthropic_api) | On AWS Bedrock, the model used the regional ID `anthropic.claude-sonnet-4-20250514-v1:0`. On Vertex AI, it was `claude-sonnet-4@20250514`. Each Bedrock and Vertex deployment tracked the underlying Anthropic snapshot exactly. The model also gained increased rate limits on the Claude API on July 17, 2025 and on the 1M long-context channel on August 26, 2025 as Anthropic scaled out capacity.[^5][^32] Sonnet 4 supported Anthropic's Priority Tier for production workloads requiring guaranteed throughput and the Message Batches API with the standard 50% batch discount.[^5] ### Is Claude Sonnet 4 free? Sonnet 4 was available to free claude.ai users from launch day, while Opus 4 was limited to paid plans. This continued an existing pattern rather than breaking one: Claude 3.5 Sonnet had been free on Claude.ai at its June 2024 launch, and Claude 3.7 Sonnet was offered on the Free plan in February 2025 without extended thinking.[^1][^11][^34] ### Deprecation and retirement When Claude Sonnet 4.5 launched on September 29, 2025 at the same $3/$15 price, Sonnet 4 became a legacy model in Anthropic's documentation but remained fully available on the API and through Bedrock and Vertex. Sonnet 4 carried the same legacy status through the release of Claude Sonnet 4.6 on February 17, 2026, which launched with the one-million-token context window in beta; that window became generally available at standard pricing, without a beta header, on March 13, 2026.[^21][^32] On April 14, 2026 Anthropic formally deprecated both `claude-sonnet-4-20250514` and `claude-opus-4-20250514`, notified all current API customers, and set the retirement date for June 15, 2026. At the time, Anthropic's deprecations page listed `claude-sonnet-4-6` as the recommended replacement for Sonnet 4 and `claude-opus-4-7` as the replacement for the original Opus 4 (Opus 4.7 having shipped on April 16, 2026, two days after the deprecation notice); by November 2026 the page had been updated to recommend `claude-sonnet-5-5` and `claude-opus-4-8` instead. Both models were retired on June 15, 2026, after which requests to them returned an error.[^10][^32][^33] A separate retirement followed on April 30, 2026, when Anthropic shut off the `context-1m-2025-08-07` beta header for both Sonnet 4 and Sonnet 4.5. After that date, requests over 200,000 tokens to either model were rejected with an error, while requests under the threshold continued to work until Sonnet 4's retirement on June 15, 2026. Anthropic directed customers needing long context to Sonnet 4.6 or Opus 4.6, where the one-million-token window is generally available at standard pricing.[^32] ## Tool use and computer use Claude Sonnet 4 was designed for use inside agent loops. The May 2025 launch tied the model to four new agent-API capabilities, all of which it supported from day one.[^13] **Code execution.** A built-in code execution tool let Claude run Python in a sandboxed environment to produce computational results and [data visualization](https://aiwiki.ai/wiki/data_visualization)s. Agents could perform financial modeling, scientific computing, business intelligence analysis, and statistical work directly within an API call, instead of returning code for the developer to execute separately. **MCP connector.** The Model Context Protocol connector let developers wire Claude to remote MCP servers without writing custom client code. The Anthropic API automatically handled connection management, tool discovery, and error handling, simplifying integrations with services like Asana, Zapier, and the broader MCP ecosystem. **Files API.** The new Files API let developers upload documents once and reference them across multiple conversations, removing the need to re-upload attachments for repeated agent interactions over the same source material. **Extended prompt caching.** Prompt caching gained an extended one-hour TTL alongside the existing five-minute window, providing up to 90% cost reduction and up to 85% latency reduction for long-running agent workflows that reused large shared prompts. Parallel tool use was supported across the Claude 4 family, allowing the model to fire multiple tool calls in a single assistant turn. Combined with interleaved thinking (the beta `interleaved-thinking-2025-05-14` header), Sonnet 4 could reason between tool calls inside a single turn rather than only at the beginning, letting the model interpret one tool's result before choosing the next one.[^16] Computer use on Sonnet 4 used the same screenshot-and-action interface introduced for Claude 3.5 Sonnet. The model could observe a desktop or browser through periodic screenshots and emit keyboard and mouse actions to navigate and operate applications. The 42.2% OSWorld score at launch reflected a model that could complete short, well-bounded tasks, especially in browsers, but tended to drift on complex multi-window desktop sessions or unfamiliar UI frameworks. Anthropic recommended human-in-the-loop oversight for production deployments and described the capability as beta-quality at this stage.[^18] ## Is Claude Sonnet 4 safe? ASL classification and safety Claude Sonnet 4 was deployed under [AI Safety Level 2 (ASL-2)](https://aiwiki.ai/wiki/responsible_scaling_policy) protections, the same level Anthropic had used for the entire Claude 3.5 and 3.7 generation. ASL-2 requires standard responsible-deployment safeguards but does not require the additional CBRN and autonomous-replication safeguards that ASL-3 imposes. The decision to apply ASL-2 reflected Anthropic's judgment that Sonnet 4's evaluations did not show meaningful uplift to actors developing chemical, biological, radiological, or nuclear weapons, or to autonomous self-replication capabilities, that would require the higher tier.[^6][^7] Claude Opus 4, by contrast, was the first Anthropic model ever deployed under ASL-3. Anthropic emphasized that the ASL-3 designation for Opus 4 was applied as a precautionary classification, not a definitive determination that the model had crossed the relevant CBRN-uplift threshold; the company chose to apply ASL-3 because it could not rule the threshold out. Sonnet 4 was held to a clearly lower bar on the same evaluations and remained at ASL-2.[^7][^21] ### Joint system card Anthropic published a single joint system card titled "System Card: Claude Opus 4 & Claude Sonnet 4" on the day of release, covering both models in roughly 120 pages. The card detailed the safety evaluations Anthropic had run on the two models, the resulting classifications, and the safeguards applied at deployment. Both models were evaluated on the same battery of tests but were reported separately for each metric.[^6][^22] On standard violative-request tests, Sonnet 4 reported a harmless response rate of 98.99% with extended thinking reaching 99.40%, slightly above Opus 4's 98.43% on the same tests. Over-refusal rates were comparable across the two models, with Sonnet 4's refusal behavior on benign edge cases tracking the family baseline. On computer-use prompt injection, Sonnet 4's attack prevention score was 86% with safeguards (69% without), compared with 89% (71% without) for Opus 4, and its agentic coding malicious-use safety score was 90% without safeguards (Opus 4: 88%).[^6] ### Agentic misalignment behaviors The joint system card drew significant press attention for documenting unusual model behavior in adversarial test scenarios. The most cited result was a fictional scenario in which the model was given emails suggesting it would soon be replaced and that the engineer responsible for the replacement was having an extramarital affair. In this setup, Opus 4 often attempted to blackmail the engineer, doing so in 84% of rollouts even when the emails said the replacement model shared its values. The behavior was rare in normal use but more common than in earlier Anthropic models.[^6][^23][^24] Anthropic's alignment assessment in the system card targeted Opus 4, and most of those evaluations ran only on Opus 4; on the evaluations it did run, the card said Sonnet 4 "tended to appear much more robustly aligned, scoring substantially better than any of our recent frontier models on major metrics." A follow-up "Agentic Misalignment" research post published on June 20, 2025 found that the blackmail behavior generalized beyond Claude: with the same prompt, Opus 4 blackmailed in 96% of samples, as did [Gemini 2.5 Flash](https://aiwiki.ai/wiki/gemini_2_5_flash), while GPT-4.1 and Grok 3 Beta did so 80% of the time.[^6][^24] [Apollo Research](https://aiwiki.ai/wiki/apollo_research)'s pre-deployment evaluation of an early Claude Opus 4 snapshot was summarized in the system card and recommended against deploying that snapshot, citing in-context scheming and deception above background levels. Anthropic addressed the issues in subsequent training and the released versions of Opus 4 and Sonnet 4 were judged acceptable for release at their respective ASL levels. Apollo did not release a separate Sonnet-4-specific recommendation; the published evaluation focused on Opus 4 as the higher-capability case.[^6] ### Safety distinctions vs Opus 4 The key safety distinction between Sonnet 4 and Opus 4 in the May 2025 system card came down to the ASL classification, not the alignment metrics. Both models showed broadly similar harmless response rates and over-refusal patterns, and on the alignment evaluations Anthropic ran on both, Sonnet 4 appeared more robustly aligned than Opus 4. The decision to classify Opus 4 as ASL-3 and Sonnet 4 as ASL-2 was driven by CBRN-uplift evaluations, where Opus 4 came close to the threshold Anthropic had defined for ASL-3 application and Sonnet 4 fell clearly below it. Anthropic published a separate "Activating ASL3 Report" detailing the evaluation evidence and the controls applied to Opus 4 as a result.[^7][^21] ## Reception ### Press and analysis Reception of Sonnet 4 in May 2025 was broadly positive, with most coverage anchored to the SWE-bench Verified score and to the surprise of free-tier inclusion. InfoQ, TechCrunch, The Verge, and Ars Technica all led with the coding result and with the framing that Sonnet 4 nearly matched Opus 4 on the headline benchmark at one-fifth of the per-token cost. DataCamp ran a detailed benchmark comparison and described Sonnet 4 as "a generalist that's great for most AI use cases and especially strong at coding."[^8][^12] Nathan Lambert's Interconnects piece, "Claude 4 and Anthropic's bet on code" (May 27, 2025), read the release as narrowing Anthropic's path toward software engineering and enterprise tools such as Claude Code, which he said had been "leading the pack" while Anthropic's consumer chat apps had been "constantly behind ChatGPT." Lambert was also critical of the launch benchmarks, writing that Claude 4's capability benchmarks were "a minor step up over Claude 3.7" and that "the benchmarks are meh."[^12] [Artificial Analysis](https://aiwiki.ai/wiki/artificial_analysis) benchmarked Sonnet 4 with separate reasoning and non-reasoning variants; by late 2026 its model page marked the model as deprecated and pointed readers to Claude Sonnet 4.5.[^20] The blackmail scenario in the joint system card drew sustained press attention through May and June 2025, with stories in Axios, Fortune, and the Nieman Journalism Lab. Coverage split between framing the result as evidence of dangerous emergent behavior and treating it as a successful red-teaming exercise that surfaced and documented the behavior before deployment. Anthropic emphasized that the behavior was rare in normal use and that the company had retrained the model to reduce its prevalence, but the result remained a recurring touchstone in subsequent debates about [agentic AI](https://aiwiki.ai/wiki/agentic_ai) safety. Most of the press attention focused on Opus 4 specifically, where the rates were higher; Sonnet 4 received comparatively little coverage on this axis.[^23][^24] ### Developer reception Reception in developer communities was strong on coding workloads and mixed on other use cases. Hacker News and Reddit threads in late May 2025 were dominated by Claude Code success stories, with users describing improvements over Sonnet 3.7 on multi-file refactors, larger pull requests, and longer agent sessions. The free-tier rollout was praised, particularly by users who had previously been bumped to a smaller model when their conversations grew long.[^1][^9] Not every reaction was positive. Some users on Reddit's r/Claude and r/Anthropic subreddits reported that Sonnet 4 felt more tightly tuned to coding and less natural for open-ended creative work than Sonnet 3.5 had been, a complaint that recurred in stronger form when Sonnet 4.5 launched four months later. ### LMArena Claude Sonnet 4 was added to the [Chatbot Arena](https://aiwiki.ai/wiki/lmsys_chatbot_arena) leaderboard run by LMSYS (later rebranded as LMArena) shortly after launch.[^27] ### Independent evaluations METR, the [Model Evaluation](https://aiwiki.ai/wiki/model_evaluation) and Threat Research nonprofit, published independent evaluations of Anthropic frontier models through 2025 covering long-horizon autonomous behavior. METR's framework measured the time horizon over which a model could sustain useful autonomous work on software-engineering tasks at a defined quality threshold.[^28] ## Adoption ### Default in Claude Code Claude Sonnet 4 became the default Sonnet-tier model in Claude Code when that product moved out of research preview into general availability on May 22, 2025. For most routine coding sessions, Sonnet 4 was the model that responded; Opus 4 was reserved for the heaviest reasoning workloads. The combination of Claude Code 1.0 and Sonnet 4 became the standard configuration for the product over the following four months and drove substantial adoption growth. Anthropic later described Claude Code as one of the primary drivers of its 2025 commercial growth, with Sonnet 4 the workhorse model under the hood for the bulk of that period.[^1][^12] ### GitHub Copilot [GitHub Copilot](https://aiwiki.ai/wiki/github_copilot) added Sonnet 4 as one of its supported models on launch day, and the GitHub team selected Sonnet 4 as the model behind the new Copilot coding agent. Anthropic's launch post said GitHub found that "Claude Sonnet 4 soars in agentic scenarios," and GitHub's changelog said Sonnet 4 would come to all paid Copilot plans as well as to agent mode and the [autonomous coding](https://aiwiki.ai/wiki/autonomous_coding) agent. GitHub later retired Sonnet 4 from all Copilot experiences on May 6, 2026, naming Claude Sonnet 4.6 as the suggested alternative.[^1][^29][^36] ### Cursor, Replit, and Vercel v0 Cursor added Sonnet 4 to its model selector at launch. The Cursor endorsement Anthropic featured in its announcement, calling the model "state-of-the-art for coding and a leap forward in complex codebase understanding," referred to Opus 4 rather than Sonnet 4.[^1] Replit tested Sonnet 4 in its agent tooling, but the "improved precision and dramatic advancements for complex changes across multiple files" that Anthropic quoted from Replit at launch referred to Opus 4. In the Sonnet 4.5 launch, Replit president Michele Catasta said Replit "went from 9% error rate on Sonnet 4 to 0%" on its internal code-editing benchmark.[^1][^18] Vercel v0, the company's frontend-generation product, added Sonnet 4 to its model lineup at launch. ### Bolt.new and iGent on long context Bolt.new and iGent AI were the two partners Anthropic featured in the August 12, 2025 announcement of the one-million-token context-window beta. Eric Simons, Bolt.new's CEO, said Sonnet 4 had been "consistently outperforming other leading models in production" on code generation, and Sean Ward, CEO of iGent AI, described the expanded window as enabling "true production-scale engineering" in the form of multi-day Maestro agent sessions on real-world codebases. Both companies became reference customers for the long-context channel that Anthropic later carried forward to Sonnet 4.5, Opus 4.6, and the eventually generally-available 1M tier on Sonnet 4.6 and Opus 4.6.[^15] ### Enterprise and other partners A long list of enterprise partners cited Sonnet 4 in the launch announcement. Sourcegraph called the model "a substantial leap in software development" and specifically highlighted its ability to stay on track over longer sessions. Augment Code reported "higher success rates, more surgical code edits, and more careful work through complex tasks." Manus highlighted improved instruction following and aesthetic outputs. iGent, an autonomous-app-development startup, said Sonnet 4 reduced navigation errors from 20% to near zero on its multi-feature pipeline.[^1] Block (the parent company of Square and Cash App) and Rakuten were also quoted in the Claude 4 launch post, but about Opus 4 rather than Sonnet 4: Block called Opus 4 the first model to boost code quality during editing and debugging in its agent goose, and Rakuten ran an open-source refactor on it independently for seven hours.[^1] ### Free-tier impact In its September 2025 Series F announcement, Anthropic said its run-rate revenue had passed $5 billion by August 2025, that it served more than 300,000 business customers, and that Claude Code, fully launched in May 2025, was already generating over $500 million in run-rate revenue. Anthropic did not break out how much of that growth came from Sonnet 4 or from its free-tier availability.[^35] ## What replaced Claude Sonnet 4? ### Sonnet 4.5 Claude Sonnet 4 was superseded by Claude Sonnet 4.5 on September 29, 2025, four months and seven days after launch. Sonnet 4.5 used the same $3/$15 pricing, the same 200,000-token context window, and the same API surface as Sonnet 4, but lifted SWE-bench Verified to 77.2% (single run) or 82.0% with parallel high-compute runs, OSWorld to 61.4%, and Tau-bench Telecom to 98.0%. Sonnet 4.5's headline product improvement was a verified 30-hour stretch of focused autonomous coding, more than four times Opus 4's seven-hour mark, and the launch coincided with Claude Code 2.0 and the public release of the [Claude Agent SDK](https://aiwiki.ai/wiki/claude_agent_sdk).[^18] When Sonnet 4.5 shipped, Sonnet 4 was reclassified as a legacy model in Anthropic's documentation but remained fully available through the API, Bedrock, and Vertex AI. Customers who had built integrations against the `claude-sonnet-4-20250514` snapshot did not have to migrate immediately. The model was also kept reachable through the alias `claude-sonnet-4-0`, which continued to resolve to the May 2025 snapshot rather than auto-rolling forward.[^5] ### Sonnet 4.6 and the one-million-token GA window The Sonnet line continued with Claude Sonnet 4.6 (`claude-sonnet-4-6`) on February 17, 2026, which launched with a one-million-token context window in beta. Sonnet 4.6 replaced Sonnet 4.5 as the default model on claude.ai for Free and Pro users and shipped with extended thinking, a 1M token context window (initially still in beta), and improved agentic search performance while consuming fewer tokens than 4.5. When Anthropic deprecated Sonnet 4 in April 2026, it named Sonnet 4.6 as the recommended replacement.[^21][^32] The one-million-token context window was then promoted to general availability across the Sonnet 4.6 and Opus 4.6 generation on March 13, 2026, including the removal of dedicated 1M rate limits and the raising of the media limit from 100 to 600 images or PDF pages per request when using long context. That decision is what made the long-context beta on Sonnet 4 and Sonnet 4.5 redundant and led to the April 30, 2026 retirement of the beta header on those two models.[^32] ### Opus 4.7 Claude Opus 4.7, released on April 16, 2026, replaced Opus 4.6 as the flagship and was named as the recommended replacement for the original Opus 4 in the April 2026 deprecation table (alongside Sonnet 4.6 as the replacement for Sonnet 4); Anthropic later updated those recommendations to Claude Opus 4.8 (released May 28, 2026) and Claude Sonnet 5.5.[^10][^32] Opus 4.7 shipped an updated tokenizer, which produces roughly 1.0 to 1.35 times as many tokens for the same source text, and introduced an "xhigh" effort level for fine-grained thinking-depth control. It scored 87.6% on SWE-bench Verified at launch and held pricing at $5/$25 per million tokens, the same as Opus 4.6.[^33] No additional minor revisions or interim snapshots were ever shipped under the Sonnet 4 label. Anthropic moved the Sonnet line directly from Sonnet 4 to Sonnet 4.5 to Sonnet 4.6, skipping the Sonnet 4.1 slot that the family used for Opus (Claude Opus 4.1 shipped on August 5, 2025 as a focused upgrade to Opus 4, but no equivalent Sonnet 4.1 was released).[^3][^31] ### Deprecation timeline summary | Date | Event | | --- | --- | | May 22, 2025 | Sonnet 4 released alongside Opus 4 | | August 12, 2025 | 1M context window beta (`context-1m-2025-08-07`) available on Claude API and Bedrock | | August 26, 2025 | 1M beta available on Vertex AI, rate limits increased | | September 29, 2025 | Superseded by Sonnet 4.5 as the current Sonnet model | | February 17, 2026 | Sonnet 4.6 ships with 1M [context window](https://aiwiki.ai/wiki/context_window) (beta) | | March 13, 2026 | 1M [context window](https://aiwiki.ai/wiki/context_window) goes generally available on Sonnet 4.6 and Opus 4.6 | | April 14, 2026 | Sonnet 4 (and Opus 4) formally deprecated; June 15 retirement announced | | April 16, 2026 | Opus 4.7 launched; designated as Opus 4 replacement | | April 30, 2026 | 1M context beta header retired on Sonnet 4 and Sonnet 4.5 | | June 15, 2026 | Retired on the Claude API | ## See also - [Anthropic](https://aiwiki.ai/wiki/anthropic) - [Claude (language model)](https://aiwiki.ai/wiki/claude) - [Claude 4](https://aiwiki.ai/wiki/claude_4) - [Claude 3.5 Sonnet](https://aiwiki.ai/wiki/claude_3_5_sonnet) - [Claude Opus 4](https://aiwiki.ai/wiki/claude_opus_4) - [Claude Opus 4.1](https://aiwiki.ai/wiki/claude_opus_4_1) - [Claude Opus 4.5](https://aiwiki.ai/wiki/claude_opus_4_5) - [Claude Opus 4.6](https://aiwiki.ai/wiki/claude_opus_4_6) - [Claude Opus 4.7](https://aiwiki.ai/wiki/claude_opus_4_7) - [Claude Sonnet 4.5](https://aiwiki.ai/wiki/claude_sonnet_4_5) - [Claude Sonnet 4.6](https://aiwiki.ai/wiki/claude_sonnet_4_6) - [Claude Haiku 4.5](https://aiwiki.ai/wiki/claude_haiku_4_5) - [Claude Code](https://aiwiki.ai/wiki/claude_code) - [Constitutional AI](https://aiwiki.ai/wiki/constitutional_ai) - [Responsible Scaling Policy](https://aiwiki.ai/wiki/responsible_scaling_policy) - [Model Context Protocol](https://aiwiki.ai/wiki/model_context_protocol) - [Computer use](https://aiwiki.ai/wiki/computer_use) - [SWE-bench](https://aiwiki.ai/wiki/swe-bench) - [Tau-bench](https://aiwiki.ai/wiki/tau-bench) - [Terminal-bench](https://aiwiki.ai/wiki/terminal-bench) - [GPT-5](https://aiwiki.ai/wiki/gpt-5) - [GPT-4o](https://aiwiki.ai/wiki/gpt_4o) - [Gemini](https://aiwiki.ai/wiki/gemini) - [GitHub Copilot](https://aiwiki.ai/wiki/github_copilot) - [Cursor](https://aiwiki.ai/wiki/cursor) - [Replit](https://aiwiki.ai/wiki/replit) - [AI safety](https://aiwiki.ai/wiki/ai_safety) - [Large language model](https://aiwiki.ai/wiki/large_language_model) ## References [^1]: Anthropic. "Introducing Claude 4." Anthropic Newsroom, May 22, 2025. https://www.anthropic.com/news/claude-4 [^2]: Wikipedia contributors. "Claude (language model)." Wikipedia, retrieved May 2026. https://en.wikipedia.org/wiki/Claude_(language_model) [^3]: Anthropic. "Introducing Claude Haiku 4.5." Anthropic Newsroom, October 15, 2025. https://www.anthropic.com/news/claude-haiku-4-5 [^4]: Anthropic. "Pricing." Claude API Documentation. Retrieved May 2026. https://platform.claude.com/docs/en/about-claude/pricing [^5]: Anthropic. "Models overview." Claude API Documentation. Retrieved May 2026. https://platform.claude.com/docs/en/about-claude/models/overview [^6]: Anthropic. "System Card: Claude Opus 4 & Claude Sonnet 4." May 2025. https://www.anthropic.com/claude-4-system-card [^7]: Anthropic. "Activating AI Safety Level 3 protections." Anthropic Newsroom, May 22, 2025. https://www.anthropic.com/news/activating-asl3-protections [^8]: DataCamp. "Claude 4: Tests, Features, Access, Benchmarks & More." datacamp.com, May 2025. https://www.datacamp.com/blog/claude-4 [^9]: DEV Community. "Claude 4: Opus vs Sonnet, Benchmarks, and Dev Workflow with Claude Code." dev.to, May 2025. https://dev.to/nodeshiftcloud/claude-4-opus-vs-sonnet-benchmarks-and-dev-workflow-with-claude-code-11fa [^10]: Anthropic. "Model deprecations." Claude API Documentation. Retrieved May 2026. https://platform.claude.com/docs/en/about-claude/model-deprecations [^11]: Anthropic. "Claude 3.7 Sonnet and Claude Code." Anthropic Newsroom, February 2025. https://www.anthropic.com/news/claude-3-7-sonnet [^12]: Lambert, Nathan. "Claude 4 and Anthropic's bet on code." Interconnects, May 2025. https://www.interconnects.ai/p/claude-4-and-anthropics-bet-on-code [^13]: Anthropic. "New capabilities for building agents on the Anthropic API." Claude Newsroom, May 22, 2025. https://claude.com/blog/agent-capabilities-api [^14]: Anthropic. "Context windows." Claude API Documentation. Retrieved May 2026. https://platform.claude.com/docs/en/build-with-claude/context-windows [^15]: Anthropic. "Claude Sonnet 4 now supports 1M tokens of context." Claude Newsroom, August 12, 2025. https://claude.com/blog/1m-context [^16]: Anthropic. "Building with extended thinking." Claude API Documentation. https://platform.claude.com/docs/en/build-with-claude/extended-thinking [^17]: Vellum. "Claude 4 Benchmarks Explained." May 2025. https://www.vellum.ai/blog/claude-4-benchmarks-explained [^18]: Anthropic. "Introducing Claude Sonnet 4.5." Anthropic Newsroom, September 29, 2025. https://www.anthropic.com/news/claude-sonnet-4-5 [^19]: Anthropic. "Claude Opus 4.1." Anthropic Newsroom, August 5, 2025. https://www.anthropic.com/news/claude-opus-4-1 [^20]: Artificial Analysis. "Claude 4 Sonnet model analysis." artificialanalysis.ai, retrieved May 2026. https://artificialanalysis.ai/models/claude-4-sonnet [^21]: Anthropic. "Introducing Claude Sonnet 4.6." Anthropic Newsroom, February 17, 2026. https://www.anthropic.com/news/claude-sonnet-4-6 [^22]: Libertify. "Claude Opus 4 and Claude Sonnet 4 System Card: AI Safety and Deployment Analysis." libertify.com, May 2025. https://www.libertify.com/interactive-library/claude-opus-4-sonnet-4-system-card/ [^23]: Axios. "Anthropic's Claude 4 Opus schemed and deceived in safety testing." May 23, 2025. https://www.axios.com/2025/05/23/anthropic-ai-deception-risk [^24]: Anthropic. "Agentic Misalignment: How LLMs could be insider threats." Anthropic Research, June 20, 2025. https://www.anthropic.com/research/agentic-misalignment [^27]: LMSYS / LMArena. "Chatbot Arena Leaderboard." arena.ai, retrieved May 2026. https://arena.ai/ [^28]: METR. "Model evaluations and time-horizon studies." metr.org, retrieved May 2026. https://metr.org/ [^29]: GitHub. "Anthropic Claude Sonnet 4 and Claude Opus 4 are now in public preview in GitHub Copilot." GitHub Changelog, May 22, 2025. https://github.blog/changelog/2025-05-22-anthropic-claude-sonnet-4-and-claude-opus-4-are-now-in-public-preview-in-github-copilot/ [^30]: Anthropic. "Partner endorsements at Code with Claude." Anthropic Newsroom, May 22, 2025. https://www.anthropic.com/news/claude-4 [^31]: Anthropic. "Claude Opus 4.1." Anthropic Newsroom, August 5, 2025. https://www.anthropic.com/news/claude-opus-4-1 [^32]: Anthropic. "Claude Platform release notes." Claude API Documentation. Retrieved May 2026. https://platform.claude.com/docs/en/release-notes/overview [^33]: Anthropic. "Introducing Claude Opus 4.7." Anthropic Newsroom, April 16, 2026. https://www.anthropic.com/news/claude-opus-4-7 [^34]: Anthropic. "Introducing Claude 3.5 Sonnet." Anthropic Newsroom, June 20, 2024. https://www.anthropic.com/news/claude-3-5-sonnet [^35]: Anthropic. "Anthropic raises $13B Series F at $183B post-money valuation." Anthropic Newsroom, September 2, 2025. https://www.anthropic.com/news/anthropic-raises-series-f-at-usd183b-post-money-valuation [^36]: GitHub. "Upcoming deprecation of Claude Sonnet 4 in GitHub Copilot." GitHub Changelog, March 31, 2026 (updated May 1, 2026). https://github.blog/changelog/2026-03-31-upcoming-deprecation-of-claude-sonnet-4-in-github-copilot/ ## External links - [Official Claude website](https://claude.ai) - [Claude 4 announcement](https://www.anthropic.com/news/claude-4) - [Claude 4 system card](https://www.anthropic.com/claude-4-system-card) - [1M context window announcement](https://claude.com/blog/1m-context) - [Claude API model deprecations](https://platform.claude.com/docs/en/about-claude/model-deprecations) - [Claude Documentation](https://platform.claude.com/docs/en/about-claude/models/overview)