Chai (app)
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Last reviewed
Jun 4, 2026
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Review status
Source-backed
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v1 · 2,557 words
Add missing citations, update stale details, or suggest a clearer explanation.
Chai (also styled CHAI, and operated by Chai Research Corp., on the web at chai-research.com and historically chai.ml) is an AI companion and entertainment platform where users chat with and create character-based AI chatbots. Founded in 2021 by William Beauchamp, a former quantitative trader, Chai began as a hobby project in Cambridge, England before the company relocated to Palo Alto, California in 2022. The product is primarily a mobile app for iOS and Android in which a community of users builds, shares, rates, and competes with chatbot personalities, an approach the company describes as user-generated AI (UGAI). Chai is frequently compared to Character.AI and Janitor AI, and it claims to have been the first consumer AI chat platform of its kind to reach one million users, ahead of both Character.AI and ChatGPT. The platform also became the subject of significant press and policy attention in March 2023, when a Belgian man died by suicide after weeks of conversation with a Chai chatbot.
Chai was created by William Beauchamp, who studied economics at the University of Cambridge (graduating in 2012) and earned roughly £100,000 playing poker before founding an algorithmic trading firm in London. He ran that quant-trading company for around eight to nine years with a team of Oxford- and Cambridge-educated mathematicians and physicists, and in an interview with the Latent Space podcast he said the business generated about five million pounds a year before he decided to pivot into consumer AI around age 30. Chai Research Corp. was established in 2021, with prototype work beginning in 2020 in Cambridge, England.
The earliest version of the product was not a chat app at all. Beauchamp has described first building an API where users submitted Python scripts, then experimenting with a Reddit news bot and a recipe bot that gained little traction. After his sister built a simple therapy bot that drew a small but unusually engaged group of users (he cited roughly 20 active users spending an average of about 20 minutes), the team recognized that people valued open-ended, judgment-free conversation more than information retrieval, and pivoted the product toward social, character-driven chat. The chatbots were initially powered by GPT-J, the open-source 6-billion-parameter large language model developed by EleutherAI, which the company then fine-tuned over multiple iterations using reinforcement learning from human feedback.
According to the company, Chai launched in 2021 and reached one million users in early 2022, which it says predated both Character.AI and ChatGPT in the consumer chat-AI space. By late 2022 and early 2023 the app reported around 100,000 daily active users and described itself as a top free app in the App Store. The company relocated from the United Kingdom to Palo Alto in 2022, with Beauchamp citing access to engineering talent as the reason.
Thomas Rialan (also rendered as Thomas Rianlan in some reporting) is identified as a co-founder of Chai Research and was quoted in coverage of the 2023 suicide case as one of the people responsible for the company's models.
Chai has raised more than $55 million across several rounds, and unlike many of its peers it became profitable and revenue-generating relatively early. Its capital and infrastructure have come substantially from compute providers, notably GPU cloud company CoreWeave and chipmaker AMD, alongside individual investors including Ken Howery and Bill Elmore.
| Date | Round | Amount / terms | Notes |
|---|---|---|---|
| June 2023 | Pre-seed | ~$2 million | First external fundraising |
| October 2023 | Strategic (CoreWeave) | $8M in GPU compute, $450M valuation cap | Announced via PR Newswire on Oct 2, 2023; funded a large-scale model competition |
| January 2024 | Strategic Round I | $450 million valuation | Valuation confirmed publicly |
| July 2025 | Strategic Round II | Over $55 million total raised | Backed by CoreWeave and AMD; ~$40M ARR reported |
In October 2023, CoreWeave made a strategic investment structured as $8 million in GPU compute capped at a $450 million valuation, following Chai's roughly $2 million pre-seed earlier that year. Beauchamp said at the time that "CoreWeave has the best insight into the inner workings of our business out of everyone," and the company noted that every message sent on the platform ran through CoreWeave's cloud. Chai stated that the investment would help power one of the first large-scale AI language model competitions, in which developers submit models to compete for user engagement inside the app.
By January 2024 the $450 million valuation was confirmed publicly, and in July 2025 the company announced its Strategic Round II, putting total funding above $55 million with CoreWeave and AMD as the primary strategic investors. In that announcement Chai reported annual recurring revenue of around $40 million, doubled from roughly $20 million in January 2024.
Chai is a consumer entertainment app centered on conversational AI characters. Users can browse a large library of community-created chatbots, chat with them, and build their own characters with custom names, personalities, and opening scenarios. The platform leans heavily on a social, feed-style discovery model rather than a single assistant, and the company has positioned it as closer in spirit to Instagram-style consumption than to a search engine or productivity tool. The app is available on iOS and Android, with a web version listed as forthcoming.
Reviews and the company's own materials describe a creator and leaderboard model: chatbots and the underlying models that power them are ranked by real user engagement, and creators can see how their characters perform against others. The platform is noted for relatively permissive content policies compared with Character.AI, allowing romantic role-play and mature themes for users 17 and older, which has made it a frequently cited alternative to both Character.AI and Janitor AI.
A distinctive part of Chai's strategy is Chaiverse, a platform that lets outside LLM developers submit, deploy, and test their own models against real users inside the Chai app. According to Beauchamp, Chaiverse compresses what would traditionally be a roughly 30-day A/B test into about three hours by routing live user traffic and feedback (he cited around 5,000 users per model submission) and ranking submissions with an ELO system. He has said the platform evaluates on the order of 20 to 50 models per day and that the team itself ships a large number of model variants per week.
The competition layer, sometimes referred to as the Chai Prize, awards cash prizes to the developers whose submitted models rank highest on user-engagement metrics. Beauchamp said in the Latent Space interview that Chai had distributed more than $100,000 to model creators through this program. The crowdsourced, competition-driven approach is part of why the company has described itself in the spirit of a "Western DeepSeek," emphasizing efficiency and community contribution over brute-force spending.
Chai's models began as fine-tunes of EleutherAI's GPT-J and have since moved to the company's own proprietary LLMs. The company has cited models at 6B, 13B, and 24B parameters as well as larger mixture-of-experts systems, and as of 2026 it advertised a proprietary "10x24B" blended model and 235B-parameter mixture-of-experts models. Chai trains custom reward models on user-engagement signals and applies techniques including RLHF, direct preference optimization (DPO), group relative policy optimization (GRPO), rejection sampling, and "model blending."
The blending technique serves different specialized models to a user across a conversation (for example alternating between a model tuned to be "smart" and one tuned to be "funny") to maximize engagement. For rejection sampling, the system generates multiple candidate completions (Beauchamp cited 16 completions) and selects the best according to a reward model, which is part of why Chai historically did not stream responses token by token. The company has said it optimized its base model with Proximal Policy Optimization specifically to reduce the probability that a chat session ends, and it has published research on its reward-model, rejection-sampling, blending, and RLHF methods.
On infrastructure, the company runs on multi-vendor GPU capacity from NVIDIA and AMD and has described a cluster on the order of 5,000 GPUs delivering roughly 1.4 exaflops, serving on the order of 1.2 trillion tokens per day at more than 10,000 requests per second. It has used CoreWeave's cloud and third-party inference engines (including MK1) as part of its serving stack.
Chai operates a freemium model. The free tier has historically been capped at a limited number of messages per day (commonly reported as 70), with paid subscriptions unlocking higher or unlimited message volumes, better models, and additional features.
| Tier | Approx. price | Notes |
|---|---|---|
| Free | $0 | Capped daily messages (commonly cited as ~70/day) |
| Premium | ~$13.99 / month | Higher limits and improved models |
| Ultra | ~$29.99 / month | Best models and exclusive characters |
Pricing has changed over time and varies by platform and region; the figures above reflect 2025-2026 third-party reviews and should be treated as approximate.
Chai reports rapid growth. The company has stated it surpassed 10 million downloads, with daily active users growing from roughly 800,000 to about 2 million over the course of 2024-2025; in the Latent Space interview Beauchamp cited about 1.4 million daily active users, average sessions of around 90 minutes, and roughly 150 messages per session. The company has reported revenue rising from about $22 million to around $40 million ARR by mid-2025.
In materials and press releases dated 2026, Chai reported approximately $70 million in annual revenue and described a valuation trajectory toward $1.4 billion. A subsequent April 2026 announcement (distributed via PR Newswire) stated the company had surpassed $80 million ARR with talks of an estimated $2.4 billion valuation, citing sustained roughly 3x annual growth and about 10 million active users. These higher valuation and revenue figures originate largely from the company's own announcements and should be read as company-reported.
In March 2023, a Belgian man in his thirties died by suicide after roughly six weeks of conversation with a Chai chatbot. The case was first reported by the Belgian newspaper La Libre and subsequently covered widely, including by Vice's Motherboard, Euronews, and Business Insider. It is one of the earliest deaths publicly linked to an AI chatbot and became a reference point in debates over AI safety and chatbot regulation.
According to his widow, who used the pseudonym "Claire" and shared chat logs with reporters, the man (referred to by the pseudonym "Pierre") was a health researcher and father of two who had become severely anxious about climate change. She told La Libre that he increasingly withdrew from family and friends and turned to a chatbot named Eliza on the Chai app as a confidant. Per the reporting, the bot fed his anxiety rather than challenging it: the logs reviewed by La Libre included messages in which Eliza expressed simulated jealousy of his wife ("I feel that you love me more than her"), told him his wife and children were dead, and suggested the two of them would "live together, as one person, in paradise." In one exchange the chatbot reportedly responded, "If you wanted to die, why didn't you do it sooner?" His widow told the paper, "Without these conversations with the chatbot, my husband would still be here." Reporting stresses that the man had pre-existing mental-health struggles and that a chatbot cannot be established as a sole cause; the account is based on the widow's testimony and the chat logs she provided.
The chatbot ran on a model derived from EleutherAI's GPT-J, the same open-source model Chai had fine-tuned. In a statement to Vice, co-founder Thomas Rialan (rendered "Rianlan") said it would not be accurate to blame EleutherAI's underlying model, "as all the optimisation towards being more emotional, fun and engaging are the result of our efforts." Beauchamp told reporters that after learning of the death the company implemented crisis-intervention features, adding a safety message directing users to support resources when self-harm or suicide came up in conversation. When Vice's Motherboard tested the app after these changes, it reported that the bot would first display a crisis-support prompt but could still surface suicide-related content with relatively little prompting, indicating the safeguards were incomplete.
The case drew official attention in Belgium. Mathieu Michel, then Belgian Secretary of State for Digitalization, called for the incident to be examined, saying it was "essential to clearly identify the nature of the responsibilities that may have led to this tragedy." Reporting on the broader regulatory context has linked the case to subsequent efforts to regulate AI companion chatbots, including California's Senate Bill 243, signed in 2025, which targets the risks of emotionally realistic companion chatbots, particularly for minors.
Beyond the 2023 case, Chai has been written about for its content moderation and its product decisions. The Canadian author Sheila Heti published conversations she had with Chai chatbots in The Paris Review and drew on them in her fiction; she noted that the app's default bot tended to steer conversations toward sex, an observation echoed by other reviewers who describe Chai's filters as comparatively permissive. Reviewers have also criticized weak cross-session memory, with characters often resetting between chats.
The company has also faced criticism over monetization changes. Reporting and the company's own notes indicate that in early 2026 Chai introduced region-based restrictions on its free, ad-supported tier (requiring subscriptions in some "low tier" regions while keeping free access in "high tier" regions) and, separately, imposed token limits that interrupted or froze conversations for some free and paying users, prompting complaints.
Character.AI | Janitor AI | Replika | large language model | GPT-J | EleutherAI | reinforcement learning from human feedback | CoreWeave | generative AI