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. The model supports building projects from scratch, feature development, debugging, large-scale refactoring, and code review. Compared to GPT-5.1, Codex is more steerable, adheres closely to developer instructions, and produces cleaner, higher-quality code outputs. Reasoning effort can be adjusted with the reasoning.effort parameter. Read the docs here
Codex integrates into developer environments including the CLI, IDE extensions, GitHub, and cloud tasks. It adapts reasoning effort dynamically—providing fast responses for small tasks while sustaining extended multi-hour runs for large projects. The model is trained to perform structured code reviews, catching critical flaws by reasoning over dependencies and validating behavior against tests. It also supports multimodal inputs such as images or screenshots for UI development and integrates tool use for search, dependency installation, and environment setup. Codex is intended specifically for agentic coding applications.
- Organization
- OpenAI
- Family
- gpt-codex
- Providers
- 10
- Context
- 400,000
- Output limit
- 128,000
- Knowledge
- 2024-09-30
- Release
- 2025-11-13
- Updated
- 2025-11-13
- Weights
- Closed
- Input
- text, image
- Output
- text
- Capabilities
- Tools, Reasoning, Structured
Providers
Compare every cataloged offer for this model, including its provider, route, token limits, price, and capabilities.
| Provider | Model ID | Context | Output | Input / output · 1M | Reasoning | Tools | Structured | Details |
|---|---|---|---|---|---|---|---|---|
| Abacus | gpt-5.1-codex | 400,000 | 128,000 | $1.25 / $10.00 | Yes | Yes | Yes | View |
| DevPass (LLM Gateway) | gpt-5.1-codex | 400,000 | 128,000 | $1.25 / $10.00 | Yes | Yes | Yes | View |
| Eden AI | azure/gpt-5.1-codex | 272,000 | 128,000 | $1.25 / $10.00 | Yes | Yes | Yes | View |
| Impossibl | openai/gpt-5.1-codex | 400,000 | 128,000 | $1.25 / $10.00 | Yes | Yes | Yes | View |
| Kilo Gateway | openai/gpt-5.1-codex | 400,000 | 128,000 | $1.25 / $10.00 | Yes | Yes | Yes | View |
| LLM Gateway | azure/gpt-5.1-codex | 400,000 | 272,000 | $1.25 / $10.00 | Yes | Yes | No | View |
| NanoGPT | openai/gpt-5.1-codex | 400,000 | 128,000 | $1.25 / $10.00 | Yes | No | No | View |
| Azurevia OpenRouter | openai/gpt-5.1-codex unknown | 400,000 | 128,000 | $1.25 / $10.00 | Yes | Yes | Yes | View |
| OrcaRouter | openai/gpt-5.1-codex | 400,000 | 128,000 | $1.25 / $10.00 | Yes | Yes | Yes | View |
| Vercel AI Gateway | openai/gpt-5.1-codex | 400,000 | 128,000 | $1.25 / $10.00 | Yes | Yes | Yes | View |
Prices and limits apply to each offer. A dash means the value is not provided. OpenRouter offers show the hosting provider and routing channel separately.
Pricing
Compare token rates and cache charges across available routes and hosting configurations.
Lowest listed input and output prices across the offers above; they may belong to different providers. These are base rates, before conditional pricing, discounts or additional fees.
openai/gpt-5.1-codexObserved - Input
- $1.25
- Output
- $10.00
- Cache read
- $0.13
Additional fees and pricing conditions
- web search
- $0.01 / search
Hosting prices through OpenRouter All endpoints and cache rates
| Endpoint | Input / 1M | Output / 1M | Cache read / 1M | Cache write / 1M |
|---|---|---|---|---|
| Azureazure | $1.25 | $10.00 | $0.13 | — |
Each row is a hosting configuration. Open an offer in Providers for its full pricing conditions and additional fees. Endpoint observations may differ from the routing catalog's base price.
Performance
Review reported latency and output-throughput percentiles from the latest observed rolling window.
Time to first token · milliseconds
All latency percentiles 1 endpoints
| Endpoint | P50 | P75 | P90 | P99 |
|---|---|---|---|---|
| Azureazure | 1,993 ms | 4,502.75 ms | 9,972.2 ms | 16,621.26 ms |
Output throughput · tokens per second
All throughput percentiles 1 endpoints
| Endpoint | P50 | P75 | P90 | P99 |
|---|---|---|---|---|
| Azureazure | 93 t/s | 105 t/s | 115 t/s | 122.56 t/s |
Percentiles describe the observed request distribution. These are snapshots of a rolling window, not a historical time series.
Uptime
Compare successful request rates across the latest 5-minute, 30-minute, and 24-hour observations.
Reported by OpenRouter at the time of collection; rate-limited requests are excluded. A dash means no measurement was reported. This is not a live availability check.
Benchmarks
Review attributed evaluation results on each source's original scale.
openai/gpt-5.1-codexObserved | Design Arena | Category | Elo | Win rate | Rank |
|---|---|---|---|---|
| agents | fullstack | 1,086 | 44.5% | 30 |
| agents | mobileapps | 1,191 | 53.4% | 18 |
| agents | webapps | 1,011 | 44% | 40 |
| models | codecategories | 1,158 | 54.6% | 73 |
| models | dataviz | 1,222 | 55.9% | 47 |
| models | gamedev | 1,151 | 50.5% | 70 |
| models | uicomponent | 1,244 | 60% | 39 |
| models | website | 1,168 | 56.1% | 76 |
Sources: Artificial Analysis and Design Arena, via OpenRouter. Scores retain their original scales and are not OpenAI Suite ratings.
Detailed evaluations
| Evaluation | Configuration | Source | Results | Details |
|---|---|---|---|---|
| models · gamedev | GPT-5.1 Codexopenai/gpt-5.1-codex-20251113 | Design Arena | 1,151 Elo | Details |
| models · website | GPT-5.1 Codexopenai/gpt-5.1-codex-20251113 | Design Arena | 1,168 Elo | Details |
| models · dataviz | GPT-5.1 Codexopenai/gpt-5.1-codex-20251113 | Design Arena | 1,222 Elo | Details |
| models · codecategories | GPT-5.1 Codexopenai/gpt-5.1-codex-20251113 | Design Arena | 1,158 Elo | Details |
| models · uicomponent | GPT-5.1 Codexopenai/gpt-5.1-codex-20251113 | Design Arena | 1,244 Elo | Details |
Sources: Artificial Analysis, Design Arena and OpenRouter. Evaluation configurations and scales differ; results are not interchangeable. Updated Oct 4, 2026.
Technical details & API
Explore specifications, supported parameters, reasoning controls, and API identifiers for each OpenRouter route.
openai/gpt-5.1-codexObserved - Context
- 400,000
- Maximum output
- 128,000
- Tokenizer
- GPT
- Input
- text, image
- Output
- text
- Moderation
- No
- Added to OpenRouter
- 2025-11-13
https://openrouter.ai/api/v1openai/gpt-5.1-codexopenai/gpt-5.1-codex-20251113Reasoning
- Required
- Yes
- Enabled by default
- Not reported
- Default effort
- medium
- Supported efforts
- high, medium, low
Supported parameters
include_reasoningmax_completion_tokensreasoningreasoning_effortresponse_formatseedstructured_outputstool_choicetoolsverbosity
Frequently asked questions
Answers based on the model metadata and serving offers currently in the catalog.
How much does GPT-5.1 Codex cost?
Listed rates start at $1.25 per million input tokens and $10.00 per million output tokens. Prices vary by provider and configuration; see Pricing for details.
Which providers offer GPT-5.1 Codex?
There are 10 cataloged offers across 10 providers. Compare model IDs, prices and limits in Providers.
What is the context window?
The cataloged model context is 400,000 tokens. Each serving endpoint may apply a different limit.
Does it support tools and structured output?
Tool calling: Yes. Structured output: Yes. Support can vary by endpoint.
Catalog history · 2 recorded revisions
Metadata observations since this model was first cataloged. These are not model release versions.
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