AI model reference · 2026
GPT-5.1-Codex
GPT-5.1-Codex is a specialized version of GPT-5.1 optimized for software engineering and coding workflows.
- Context window
- 400,000 tokens
- Maximum output
- 128,000 tokens
- Base provider API input
- $1.25 / 1M tokens
- Base provider API rate
- Published evidence
- 1 benchmark, 1 Arena result
Overview
About GPT-5.1-Codex
A concise catalog overview. Technical limits and published evaluation evidence are listed separately below.
GPT-5.1-Codex is a specialized version of GPT-5.1 optimized for software engineering and coding workflows.
Published evaluations
Benchmark results
Only results mapped to this exact model and backed by a named source appear here. Different evaluation protocols are not treated as interchangeable.
| Benchmark | Score | Evaluation details | Source |
|---|---|---|---|
| SWE-Bench VerifiedA human-validated subset of real GitHub issues used to measure whether a coding agent can produce repository patches that resolve the associated tests. | 66.0% | ResolvedVersion: SWE-Bench Verified 500 · Split: Verified, 500 tasks · Harness: mini-SWE-agent / version 1.16.0 · Attempts: One attempt · Reasoning effort: mediumProtocol note: Harness version: 1.16.0; Run date: 2025-11-24Methodology | SWE-benchBenchmark owner |
Human preference
Arena results
Arena scores come from blind human preference votes. They are reported separately from task benchmarks and are not used as substitutes for missing benchmark results.
| Category | Score | Rank | Votes | Status |
|---|---|---|---|---|
| Arena WebDevBlind human preference score for code and web development. | 1,336±12 | #92 | 4,873 | Published |
Technical reference
Specifications and API facts
Technical limits and reference provider prices come from the current catalog unless a reviewed external source is listed. Missing values stay marked as unavailable.
- Provider
- OpenAI
- Release date
- Not available in reviewed sources
- Catalog added
- Nov 13, 2025
- Context window
- 400,000 tokens
- Maximum output
- 128,000 tokens
- Knowledge cutoff
- Not available in reviewed sources
- License
- Not available in reviewed sources
- Input types
- Text, Image
- Output types
- Text
- Reasoning
- Supported
- Provider endpoint tool parameters
- Accepts tool parameters
- Base provider API input
- $1.25 / 1M tokens
- Base provider cached input
- $0.13 / 1M tokens
- Base provider API output
- $10 / 1M tokens
These are reference provider API rates, not Writingmate checkout charges. Access in Writingmate follows the allowances of your Writingmate plan.
Provenance
Sources and update status
Source links are attached to the facts and evaluations they support. Catalog-only values are not presented as independently verified claims.
- Arena WebDevArena AI · Retrieved Aug 25, 2026
- SWE-bench Verified Bash Only LeaderboardSWE-bench · Retrieved Aug 9, 2026
- OpenRouter model catalogOpenRouter
Evidence last updated Aug 25, 2026.
Catalog record updated Nov 13, 2025.
Catalog-added dates describe when a model entered the catalog, not necessarily its public release date.
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