GPT-5.1-Codex
openai/gpt-5.1-codex-20251113
OpenAI's GPT-5.1-Codex, released on 2025-01-01, accepts text and image inputs and generates text output. It supports tool use and reasoning, has a context length of 400 000 tokens, and its weights are not open. Pricing is $1.25 per million input tokens and $10 per million output tokens.
- tool use
- structured outputs
- reasoning
At a glance
Specifications
What the API gives you
- Context window
- 400K tokens
- Max output
- 128K tokens
- Input price
- $1.25 / 1M tokens
- Output price
- $10 / 1M tokens
- Cache read
- $0.13 / 1M tokens
- Modalities
- text, image → text
- Knowledge cutoff
- —
- Released
- Jan 1, 2025
Measured evidence
Public benchmark record
- Design Arena Coding
- 1154 Elo2026-10-21
- Design Arena Full-stack Agent
- 1086 Elo2026-10-14
- Design Arena UI
- 1237 Elo2026-10-21
- Design Arena Web-app Agent
- 1018 Elo2026-10-21
- Design Arena Website
- 1163 Elo2026-10-21
LMArena data licensed CC-BY-4.0. Aider (Apache-2.0) and SWE-bench (MIT) are open. Design Arena uses blind human preference.
Task evidence
How broad is the support?
Each status is exact to this model version and the selected task. Official release claims remain provisional.
- Best LLM for Frontend & UIProvisional evidence
55% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from LiveBench Coding or LMArena WebDev. 6 of 6 configured evaluation feeds currently have results.
- Best LLM for Agentic CodingProvisional evidence
20% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from LiveBench Agentic Coding or LMArena Agent. 7 of 7 configured evaluation feeds currently have results.
- Best LLM for CodingProvisional evidence
16% of intended weighted task evidence across 1 independent source; broader independent confirmation is still missing from Aider Polyglot or LiveBench Coding. 7 of 7 configured evaluation feeds currently have results.
Recommendation coverage
Where this model appears
Not currently included in a published recommendation. The task evidence panel above says exactly what is confirmed and what is still missing.
Catalog data via OpenRouter and models.dev. Last checked within the past 6 hours.