GPT-5.1 Codex
GPT-5.1 Codex is worth evaluating for coding, rag, and agents when its provider route and context window match the workload.
Use it for
- Teams evaluating coding, rag, and agents
- Workloads that can use a 400k context window
- Buyers comparing 2 tracked provider routes
Do not use it for
- Workloads where another current model has stronger sourced task evidence
- Family
- GPT-5.1
- Released
- 2025-12-01
- Context
- 400k
- Architecture
- Decoder Only
- Knowledge cutoff
- 2024-09
- Specialization
- code
- Openness
- Proprietary
- License
- ProprietaryCommercial use: conditional
- Training
- Pretrained
Cheapest of 2 routes · OpenRouter · cache read $0.130
About
GPT-5.1-Codex is a coding-specialized version of GPT-5.1, optimized for software engineering and agentic coding workflows at 400K context.
GPT-5.1 Codex is a proprietary model in the GPT-5.1 family. The structured metadata tracks a 400k-token context window, multimodal input, function calling, tool use, structured outputs, and code execution. This page tracks provider routes through OpenRouter and Vercel AI Gateway, with the cheapest tracked route listed at $1.25 input and $10 output per 1M tokens. No headline benchmark score is tracked for GPT-5.1 Codex yet.
Top use-case fit: coding, agents, and build tasks
Coding
Included by capability and metadata signals in the decision map.
RAG
Included by capability and metadata signals in the decision map.
Agents
Included by capability and metadata signals in the decision map.
Provider price ladder
Compare all 2Compare API pricing across 2 providers for input and output tokens, batch, and cached reads when available.
| Provider | Input / 1M | Output / 1M | Cache | Route |
|---|---|---|---|---|
| OpenRouter | $1.25 | $10.00 | read $0.130 | Serverless |
| Vercel AI Gateway | $1.25 | $10.00 | read $0.125 | Serverless |
Capabilities
Benchmark peer barsfor Coding
No task-mapped benchmark peers are available for this model yet.
Migration checks
No linked migration route is available for this model yet.
Comparison and alternatives
Browse all comparisons →Cheapest of 2 routes · OpenRouter · cache read $0.130