OpenRouter

OpenRouter is a unified API gateway platform and marketplace that provides developers with access to over 400 large language models (LLMs) from multiple providers through a single, standardized interface. Founded in early 2023 by Alex Atallah, co-founder and former CTO of OpenSea, and engineer Louis Vichy, the platform aims to simplify the integration and optimization of AI models while providing price transparency, reliability, and consolidated billing.

Overview

OpenRouter functions as an intermediary service and the first LLM marketplace, normalizing access to various AI models through a consistent API schema compatible with OpenAI's Chat API. This allows developers to switch between different LLM providers without changing their code implementation, addressing the problem of "API sprawl" where developers would otherwise need to maintain separate integrations for each model provider.

The platform operates as a remote-first company headquartered in New York City, with additional offices in San Francisco, California. As of 2025, the company has 8 employees and serves over 2.5 million developers.

The service supports a growing catalog of over 400 models from 60+ providers including OpenAI, Anthropic, Google, Mistral AI, Meta, DeepSeek, xAI, and various open-source implementations. The platform adds approximately 25-40 milliseconds of edge latency to end-to-end inference for most requests while providing automatic failover, load balancing, and unified billing.

History

OpenRouter was founded in February/March 2023 by Alex Atallah, shortly after witnessing the emergence of open-source LLMs like Meta's LLaMA. The initial inspiration came after Atallah observed models like Stanford's Alpaca, which demonstrated that smaller teams could create competitive AI models with minimal resources. This suggested a future ecosystem with numerous specialized models, potentially requiring a marketplace to effectively navigate them.

Atallah, who previously co-founded the $14 billion NFT marketplace OpenSea and served as Director of Product & Engineering at Kaggle, partnered with engineer Louis Vichy and one of his collaborators from the browser extension framework Plasmo to launch OpenRouter.

In its early stages, OpenRouter processed approximately 10 trillion tokens annually. By mid-2025, it had scaled to over 100 trillion tokens per year, representing a 10x growth. A key milestone was serving as the exclusive launch partner for OpenAI's first coding model, GPT 4.1 (released as Quasar Alpha on the platform).

Funding

In June 2025, OpenRouter announced back-to-back seed and Series A rounds totaling $40 million, achieving a valuation of approximately $500 million:

Round	Date	Amount	Lead Investor	Other Participants	Valuation
Seed	June 2025	$12.5 million	Andreessen Horowitz	Sequoia Capital, Soma Capital	-
Series A	June 2025	$28 million	Menlo Ventures	Sequoia Capital, Transpose Platform Management	~$500 million
Total		$40.5 million

Monthly customer spending through the platform grew from $800,000 in October 2024 to approximately $8 million in May 2025, a ten-fold increase in seven months.

Technical Implementation

API Architecture

OpenRouter provides a single API endpoint at `https://openrouter.ai/api/v1` that implements the OpenAI API specification for `/completions` and `/chat/completions` endpoints. The platform normalizes request/response schemas across providers to reduce per-vendor integration work, while still allowing provider-specific options to pass through when needed.

Key technical features include:

• Bearer token authentication with OAuth PKCE support for user delegation
• GitHub secret scanning partnership for exposed key detection
• SSE streaming for real-time response handling
• Normalized token counting based on the GPT-4o tokenizer for consistency

Supported Parameters

The API supports comprehensive parameters for model configuration:

Parameter	Description	Range/Values
temperature	Controls response randomness	0-2
max_tokens	Maximum response length	Model-dependent
top_p	Nucleus sampling threshold	0-1
frequency_penalty	Reduces repetition of frequent tokens	-2 to 2
presence_penalty	Reduces repetition of any used tokens	-2 to 2
stream	Enables SSE streaming	true/false
tools	Function calling configuration	JSON schema
response_format	Enforces structured output	JSON schema

Provider Routing

OpenRouter employs intelligent routing algorithms that consider multiple factors:

Routing Method	Identifier Suffix	Description	Use Case
Default	(none)	Load balances across providers, prioritizing price	General purpose
Nitro	:nitro	Optimizes for throughput and response speed	Time-sensitive applications
Floor	:floor	Prioritizes the lowest cost options	Budget-conscious deployments
Online	:online	Includes web search results via Exa.ai	Real-time information needs
Auto	openrouter/auto	AI-powered model selection using NotDiamond	Automatic optimization
Custom	User-defined	Specific provider preferences	Enterprise requirements

The system automatically falls back to alternative providers when the primary endpoint returns errors or exceeds latency thresholds, improving overall reliability to maintain uptime.

Features and Functionality

Model Catalog

OpenRouter provides access to over 400 models across multiple tiers and providers:

Provider	Example Models	Use Cases	Pricing Tier
OpenAI	GPT-5 Chat, GPT-4o, GPT-4 Turbo, GPT-4o Mini, o1-preview	General purpose, coding, reasoning	Premium to Budget
Anthropic	Claude Opus 4, Claude 3.5 Sonnet, Claude 3 Haiku	General reasoning, coding, multilingual	Premium to Budget
Google	Gemini 2.5 Pro, Gemini 2.5 Flash, Gemini 2.0 Flash	Multimodal, research, creative tasks	Mid-tier to Budget
Mistral AI	Mistral Large 2, Mistral Nemo, Codestral	Coding, multilingual, efficiency	Mid-tier
Meta	Llama 3.1 (405B, 70B, 8B), Llama 3.2	Open-source, text generation	Free to Budget
DeepSeek	DeepSeek Coder V2, DeepSeek R1	Coding, specialized tasks	Free tier available
xAI	Grok	General AI, X platform integration	Premium
Perplexity AI	Search-enhanced models	Research, knowledge retrieval	Mid-tier
Others	Kimi-K2, Moonshot, various Hugging Face models	Specialized tasks, community models	Various

Multimodal Support

The platform supports multimodal inputs where the underlying models allow it:

• Image processing and analysis with vision-capable models
• PDF document parsing with OCR capabilities
• Audio input processing for transcription and analysis
• Structured data extraction from documents
• Video processing support (planned as of 2025)

Web Search Integration

OpenRouter offers web search augmentation through integration with Exa.ai. Appending `:online` to any model identifier enables real-time web search capabilities, with retrieved information injected into the model context with proper citations. This feature is priced at $4 per 1,000 search results.

Advanced Capabilities

• Structured Outputs: JSON schema enforcement via `response_format` parameter for predictable parsing
• Tool/Function Calling: Support for parallel tool calls with `tools` and `tool_choice` parameters
• Context Caching: Optimization for repeated prompts to reduce costs and latency
• Reasoning Tokens: Reveals model thinking processes for complex tasks with configurable token budgets
• Community Leaderboards: Public rankings showing model usage statistics, performance metrics, and user votes

Analytics and Observability

OpenRouter provides comprehensive analytics dashboards showing:

• Token consumption and costs across models
• Latency metrics and performance trends
• Error rates and failure analysis
• Usage patterns by application, team, or API key
• Real-time monitoring and status updates

The platform also offers programmatic access to usage data via the `/api/v1/generation` endpoint for integration with custom monitoring systems.

Pricing and Billing

Cost Structure

OpenRouter uses a credit-based prepaid system with pass-through pricing:

• Model Costs: Direct per-token charges from underlying providers, billed separately for input and output tokens
• Platform Fee: Approximately 5% cut of inference costs as primary revenue
• Credit Purchase Fee: 5.5% fee (minimum $0.80) for credit card purchases, or 5.0% for cryptocurrency payments in USDC

Example model pricing (as of October 2025):

Model	Input (per million tokens)	Output (per million tokens)
GPT-5 Chat	$1.25	$10.00
Claude Opus 4	$15.00	$75.00
Claude 3.5 Sonnet	$3.00	$15.00
GPT-4o	$2.50	$10.00
Gemini 2.5 Flash	$0.15	$0.60
Mistral Large 2	$2.00	$6.00
GPT-4o Mini	$0.15	$0.60
DeepSeek Coder V2	$0.27	$1.10
Llama 3.1 8B	Free (limited)	Free (limited)

Credits are purchased in bundles (for example $10 for 10 credits) with no expiration date, and volume discounts are available for enterprise customers.

BYOK (Bring Your Own Keys)

For enterprise users with existing provider relationships, OpenRouter supports BYOK:

• First 1 million BYOK requests per month are free
• Subsequent requests incur a 5% fee of the normal OpenRouter cost
• Support for keys from Azure, AWS Bedrock, Google Vertex AI, and other providers
• Automatic fallback to OpenRouter credits if user keys encounter issues

Free Tier

OpenRouter offers a free tier with the following limits:

• Users with less than 10 credits: 50 free model requests per day
• Users with 10+ credits: 1,000 free model requests per day
• Free model variants (`:free`) limited to 20 requests per minute
• Access to selected free models including DeepSeek Coder, Llama variants, and Devstral Small

Privacy and Security

Data Retention

OpenRouter's default privacy configuration includes:

• Prompt and response content storage disabled by default
• Only request metadata (timestamps, model used, token counts, latency) retained
• Opt-in prompt logging available, sometimes with associated discounts for model improvement

Zero Data Retention (ZDR) Routing

Users can configure requests to route only to providers with verified zero data retention policies. This feature may limit model availability and potentially affect latency or pricing but provides enhanced privacy guarantees for sensitive applications.

Compliance

As of July 2025, OpenRouter has achieved SOC 2 Type I compliance and maintains a public trust portal detailing security practices and compliance status. The platform implements Cloudflare DDoS protection and rate limiting for security.

Integration and Ecosystem

SDK and Framework Support

OpenRouter provides official support for numerous SDKs and frameworks:

• OpenAI SDK (Python and TypeScript) - drop-in compatible
• LangChain (Python and JavaScript)
• Vercel AI SDK
• PydanticAI
• LlamaIndex
• Langfuse for observability
• Continue (VS Code extension)
• Cline (AI coding assistant)
• Zapier for workflow automation
• Home Assistant for home automation

Third-Party Integrations

• Cloudflare AI Gateway for additional routing and caching
• NovelCrafter for creative writing applications
• Various IDE extensions

Developer Tools

The platform offers various tools for developers:

• Interactive Request Builder for generating API requests
• Public leaderboards showing model usage statistics
• Real-time monitoring and analytics dashboards
• GitHub repository with example code and integrations
• Discord community for developer support

Business Model and Market Position

Revenue and Growth

According to company statements, OpenRouter's business model centers on:

• 5% cut of inference costs as primary revenue source
• Projected $25 billion AI inference market in 2025
• $15 billion addressable market from third-party applications

Co-founder Chris Clark stated: "We believe that inference costs will eclipse salaries as the dominant operating expense for most knowledge-based companies over the next five to 10 years."

The platform has facilitated significant market transparency in AI model pricing and performance. Market share data from August 2025 reveals Google (22.5%) and Anthropic (22.3%) as leading providers, followed by OpenAI and various open-source providers.

Competition

OpenRouter operates in the LLM benchmarking and model routing market. Major competitors include:

• Together AI - Focus on open-source models and fine-tuning
• AWS Bedrock - Deep AWS integration for enterprise
• Helicone - Observability-focused gateway
• Stability AI, LangChain, Fetch.ai, Lamini, MI2.ai

User Base

As of 2025, OpenRouter serves:

• Over 2.5 million developers
• Applications processing 100+ trillion tokens annually
• Notable integrations including Cline and native Visual Studio Code support

The platform has received endorsements from prominent figures in the AI community, including Andrej Karpathy, who highlighted its LLM rankings during a talk at Y Combinator Startup School on June 17, 2025.

Leadership

Founders and Executive Team

• Alex Atallah - Founder and CEO
  • Previously co-founder and CTO of OpenSea ($14 billion valuation)
  • Former Director of Product & Engineering at Kaggle

• Louis Vichy - Co-founder and Engineer

• Chris Clark - COO

Investors

Notable investors include:

• Andreessen Horowitz (a16z) - Seed lead
• Menlo Ventures - Series A lead
• Sequoia Capital
• Soma Capital
• Transpose Platform Management
• Y Combinator

Principles and Philosophy

OpenRouter's stated principles emphasize a multi-model and multi-provider future for AI development. The company highlights several key value propositions:

• Model diversity and choice for developers
• Price transparency without hidden markups on inference costs
• Reliability through automatic failover and load balancing
• Simplified integration across multiple providers
• Support for both commercial and open-source models
• Democratization of AI access through unified interfaces

See Also

• API gateway
• Large language model
• OpenAI
• Anthropic
• Google AI
• AI infrastructure
• Machine learning operations
• Model serving
• Prompt engineering
• MLOps

External Links

• OpenRouter Documentation
• OpenRouter on GitHub
• OpenRouter on X (Twitter)
• OpenRouter Discord Community