What this is
01.AI (Kai-Fu Lee's lab) shipped the Yi line as a pioneering open-weight Chinese LLM family, with Yi-Lightning hitting #6 on Chatbot Arena at a fraction of OpenAI's cost. This page is a 2026-05-15 release-by-release reference.
Yi Release Timeline
| Date | Release | Notable |
|---|---|---|
| Nov 2023 | Yi-34B / Yi-6B (open-weights) | Bilingual Chinese-English foundation |
| 2024 (mid) | Yi-Large (proprietary) | API-only flagship |
| Sep 2024 | Yi-Coder (1.5B, 9B) | 52 programming languages; 128K context |
| Oct 16, 2024 | Yi-Lightning (proprietary) | #6 on Chatbot Arena; $0.14/M tokens |
| Oct 2024 | Yi-Lightning-Lite | Cheaper variant for high-volume |
Yi Family at a Glance
| Model | Category | License | Best at |
|---|---|---|---|
| Yi-34B / 6B | Foundation open-weights | Apache-style | Bilingual Chinese-English foundation |
| Yi-Coder (1.5B, 9B) | Coding | Open-weights | 52 languages, 128K context, small footprint |
| Yi-Large | Flagship | Proprietary API | General-purpose performance |
| Yi-Lightning | Cost-efficient flagship | Proprietary API | Quality near GPT-class at low cost ($0.14/M) |
Six Things the Lineage Tells You
- 01.AI was the first to demonstrate Chinese open-weight LLM viability at scale. Yi-34B in late 2023 preceded much of the current Chinese open-weight wave.
- Yi-Lightning at $0.14/M tokens vs GPT-o1-mini at $0.26/M showed Chinese labs could undercut OpenAI on price while landing in the top-10 of Chatbot Arena.
- Yi-Coder's 128K context at 1.5B and 9B params punched well above its weight for small-model coding.
- 01.AI's release cadence slowed in 2025-2026 relative to peers. DeepSeek, Qwen, GLM, Kimi all out-released 01.AI through 2025.
- The Yi line shifted toward closed-tier flagship (Yi-Large, Yi-Lightning). Foundation tier (Yi-34B / Yi-Coder) remains open; flagship is API-only.
- Kai-Fu Lee's profile keeps 01.AI globally visible even as its release pace lags newer Chinese labs.
What This Means for AI Visibility
Yi-Coder remains popular for on-prem code-completion deployments at small organisations because of its size-to-performance ratio. Yi-Lightning sees use in cost-sensitive customer-support deployments. Brand visibility on Yi-powered surfaces is concentrated in cost-sensitive Chinese enterprise + global indie deployments.
Methodology
Release dates from Wikipedia 01.AI, 01.AI Yi GitHub, Yi-Coder GitHub, Yi-Lightning Technical Report (arXiv), and MarkTechPost on Yi-Coder release.
How Presenc AI Helps
Presenc AI tracks brand visibility on Yi-served API surfaces for the cost-sensitive enterprise segment. Yi remains an important small-model coding option even as the headline Chinese LLM news shifts toward newer labs.