GPT-5.1-Codex vs Yi-Lightning
How do these models stack up? Below is an expert side-by-side comparison of specifications, context window capacity, live pricing per million tokens, and standardized benchmark scores for GPT-5.1-Codex and Yi-Lightning.
GPT-5.1-Codex
GPT-5.1-Codex is a specialized version of GPT-5.1 optimized for software engineering and coding workflows. It is designed for both interactive development sessions and long, independent execution of complex engineering tasks....
Yi-Lightning
Yi-Lightning is 01.AI's (ιΆδΈδΈη©) fastest and most cost-efficient model, purpose-built for high-throughput production workloads. It delivers competitive performance against GPT-4o-mini and Claude Haiku at a fraction of the cost, with exceptional bilingual Chinese-English capabilities. Yi-Lightning excels at classification, entity extraction, summarization, and high-frequency API tasks where latency and cost-per-call are critical constraints.
Technical Specifications
| Specification | GPT-5.1-Codex | Yi-Lightning |
|---|---|---|
| Provider | OpenAI | 01.AI |
| Context Window | 400,000 tokens | 131,072 tokens |
| Agent Suitability | N/A | 82/100 |
| Time to First Token (TTFT) | N/A | 120 ms |
| Deployment Model | managed api | managed api |
| Production Stability | stable | stable |
| API Available | Yes | Yes |
| Released Date | 2025-11-13 | 2025-10-01 |
API Pricing Comparison
Input Price per Million Tokens
GPT-5.1-Codex
$1.25
Yi-Lightning
$0.15
Output Price per Million Tokens
GPT-5.1-Codex
$10.00
Yi-Lightning
$0.30
Want to test both models live?
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Benchmark Performance Metrics
Scores show the raw performance percentages verified across key evaluation suites. Higher bars indicate superior accuracy and capability in that domain.
GPT-5.1-Codex Quirks & Gotchas
No developer gotchas reported.
Yi-Lightning Quirks & Gotchas
- βΈBest cost-efficiency for high-volume bilingual applications
- βΈSelf-hostable via Ollama β excellent open-weight option for Asian-language pipelines