Yi-Large / Yi-1.5 / Yi-Lightning is a LLM family from 01.AI (China).
One-line fit: best used for CN/EN applications.
Key specifications
| Provider | 01.AI |
|---|---|
| Model | Yi-Large / Yi-1.5 / Yi-Lightning |
| Type | LLM family |
| Context window | Up to 200K class variants |
| Pricing (indicative) | Open + API |
| Company category | Frontier Lab |
| Region | China |
| Official site | https://www.01.ai |
Benchmarks and public standing
Top open bilingual scores at releases
Treat scores as directional. SWE-bench, Terminal-Bench, LMSYS Arena, Artificial Analysis, and vendor cards use different harnesses and are not always comparable 1:1. Re-check the latest official model card before decisions.
What this model is good at
CN/EN applications
This aligns with 01.AI’s broader strengths:
- Open bilingual models
- Efficient architecture
- Developer open releases
Limitations and watch-outs
Funding/market shifts affected pace
- Rate limits, regional availability, and data retention policies vary by plan.
- Agent harness quality (Cursor, Claude Code, Codex, custom tools) can change outcomes more than raw model Elo.
- Open-weight availability (if any) is separate from hosted API quality and safety filters.
Ideal users
- Product engineers shipping features that match: CN/EN applications
- Teams standardizing on the 01.AI ecosystem
- Agent builders who need a LLM family
When to pick something else
- Cheaper volume: compare lower tiers from the same lab or open Chinese/EU alternatives.
- Maximum hard SWE thoughtfulness: compare Claude Fable-class and other coding flagships.
- Giant multimodal corpora / Workspace: compare Gemini-class models.
- Self-host / open weights: Llama, Qwen, DeepSeek, GLM, Mistral open lines.
Parent company
01.AI – Kai-Fu Lee lab; Yi open models known for strong bilingual performance.
Related models from 01.AI
Data is curated for AIForumSphere model directory mid-2026 directional figures.
