Yi Model
01.AI's open bilingual models, frozen since 2024; the paid API closed in 2026
Overview
Yi is the Chinese-English model family 01.AI released from November 2023: Yi-6B, Yi-34B, Yi-1.5 and Yi-Coder as Apache 2.0 open weights, plus the API-only Yi-Large and Yi-Lightning. 01.AI stopped training its own large models in 2025 and closed the Yi API on 3 September 2026, so only the downloadable weights remain.
Pricing
Pricing shown for reference only. These figures reflect RECATOOLS research as of 14 Oct 2026 and may be out of date or incomplete. This is not financial or purchasing advice — always confirm the current price on the provider’s official website before making any decision.
Use cases
What you can produce with Yi Model
- Self-hosted bilingual Chinese-English text generation from Apache 2.0 weights
- Long-document work with the Yi-6B-200K and Yi-34B-200K context variants
- Code completion and generation with the Yi-Coder 1.5B and 9B models
- A licence-clean base model for fine-tuning, including commercial use
- Continued operation of existing Yi deployments without vendor lock-in
Yi is now a finished product line. The open weights, from Yi-6B to Yi-1.5 and Yi-Coder, remain free under Apache 2.0 and are still a usable bilingual Chinese-English base, especially for teams that already deployed them. Nothing new has been released since 2024.
The paid side is gone: 01.AI shut its Yi API on 3 September 2026, taking Yi-Lightning with it, and the company now sells enterprise decision tools and consulting instead. Keep existing Yi deployments if they work; start new ones on a model that is still maintained.
What we found
Yi is the model family that 01.AI (零一万物), the Beijing start-up led by Kai-Fu Lee, released from November 2023. The first open models, Yi-6B and Yi-34B, came with long-context 200K variants, and TechCrunch reported at launch that Yi-34B ranked first among pre-trained models on Hugging Face's leaderboard. Yi-1.5 and Yi-Coder followed in 2024, all under the Apache 2.0 licence. The larger Yi-Large and Yi-Lightning, the October 2024 model 01.AI says ranked sixth on the LMSYS arena, were sold only through its API and never released as weights.
Then 01.AI changed course. In a March 2025 interview with the South China Morning Post, reported by The Decoder, Lee said the company had abandoned training its own large models and would build on DeepSeek's open models instead, arguing that only firms with hundreds of millions of users can justify pretraining. 01.AI launched an enterprise platform, WorldWise (万智), announced as unlocking DeepSeek for companies, though its Chinese site now describes it as built on its own model stack. Its 2026 products are decision tools for executives under the TrueNorth (万策) name, consulting, and sovereign AI work such as Q.AI, a joint venture with Kazakhstan. Bloomberg reported in July 2026 that 01.AI was raising a pre-IPO round ahead of a Hong Kong listing planned for 2027.
The decisive change for this page is that the Yi API has closed. A notice on 01.AI's developer platform dated 3 August 2026 stopped new sign-ups and top-ups, ended Yi-Lightning and Yi-Vision calls on 3 September 2026, and left a refund window open until 3 December. The international platform had already gone dark.
What remains is the open weights. Yi-6B, Yi-34B, Yi-1.5 and Yi-Coder are still on Hugging Face under Apache 2.0, free for commercial use, and untouched since late 2024. They are still a reasonable bilingual Chinese-English base for teams that already run them. For a new project, newer open models are the better place to start.
Compiled by RECATOOLS from public sources: vendor documentation and pricing, code repositories and published reporting.
Notable facts
- 01.AI raised $200 million at a $1 billion valuation in 6 months — one of the fastest unicorn valuations in Chinese AI history.
- Yi-34B was trained on 3 trillion tokens, significantly more than comparable Western models at its release, giving it broader knowledge coverage.
- Kai-Fu Lee, Yi's founder, is the author of 'AI Superpowers', the most widely read book on US-China AI competition.
Frequently asked questions
About this listing
This entry was compiled from publicly available data including Yi Model's official website, press releases, documentation, and reputable third-party publications. RECATOOLS is not affiliated with Yi Model unless explicitly stated.
Third-party AI tools update their pricing, features, availability, and policies frequently. Information here may be outdated by the time you read this — we make reasonable efforts to keep listings current, but cannot guarantee absolute accuracy.
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