---
id: "openai/gpt-5.1-codex"
also: ["openai/gpt-5.1-codex-20251113", "requesty/openai/gpt-5.1-codex", "vercel/openai/gpt-5.1-codex"]
cheapest_list_usd_per_m: "1.125 in, 9.0 out, at openai-responses on requesty"
cheapest_effective_usd_per_m: "0.1959 in, 10.0 out, at azure on vercel"
context: 400000
max_output: 128000
input: ["text", "image"]
output: ["text"]
released: "2025-11-13"
reasoning: ["high", "medium", "low"]
api: ["/api/v1/chat/completions", "/api/v1/completions", "/api/v1/messages", "/api/v1/responses"]
params: ["include_reasoning", "max_completion_tokens", "max_tokens", "reasoning", "reasoning_effort", "response_format", "seed", "stop", "structured_outputs", "temperature", "tool_choice", "tools", "verbosity"]
endpoints: 3
gateways: "openrouter (1), requesty (1), vercel (1)"
no_training: 3
trains: 0
retains_prompts: 1
---
# OpenAI: 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....