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Favicon for openai

OpenAI: GPT-5.1-Codex

openai/gpt-5.1-codex

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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 hereOpens in new tab

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.

Modalities
In / Out Price
$1.25 / $10per 1M
Context
400K
Released
Nov 13, 2025
Compare
ProvidersPricingPerformanceUptimeBenchmarksAppsActivityFAQExplore

Providers

This model is hosted by one provider. OpenRouter forwards every request to it directly — no routing decisions to make.

Pricing

The average price customers actually pay for this model, next to the prices providers post. Caching and discounts mean the price actually paid is often well below the listed one.

Performance

Throughput is how fast the model writes (tokens per second — higher is better). Latency is total round-trip time (lower is better). TTFT is time-to-first-token — how long before you see anything appear (lower is better).

Uptime

Uptime is the percentage of the past 3 days that at least one provider was responding to requests. Availability is the percentage of time that inference was successfully served. OpenRouter continuously monitors and uses the next-best provider when one returns an error.

Benchmarks

Scores on standardized evaluations and this model’s own outputs on shared benchmark prompts. Higher percentages are better — and each rank shows where this model lands among the models evaluated on that source.

Benchmark score summary for OpenAI: GPT-5.1-Codex (Artificial Analysis, Design Arena and Vals AI)
SourceBenchmarkScore
Artificial AnalysisGPT-5.1 Codex (High) Math Index95.7
Artificial AnalysisGPT-5.1 Codex (High) GPQA Diamond86.0%
Artificial AnalysisGPT-5.1 Codex (High) HLE25.7%
Artificial AnalysisGPT-5.1 Codex (High) IFBench70.0%
Artificial AnalysisGPT-5.1 Codex (High) τ²-Bench Telecom83.0%
Artificial AnalysisGPT-5.1 Codex (High) AA-LCR69.3%
Artificial AnalysisGPT-5.1 Codex (High) CritPt5.7%
Artificial AnalysisGPT-5.1 Codex (High) LiveCodeBench84.9%
Artificial AnalysisGPT-5.1 Codex (High) Terminal-Bench Hard34.8%
Artificial AnalysisGPT-5.1 Codex (High) MMLU-Pro86.0%
Artificial AnalysisGPT-5.1 Codex (High) AIME 202595.7%
Design ArenaGPT-5.1 Codex Agents Arena Full Stack Elo1086
Design ArenaGPT-5.1 Codex Agents Arena Mobile Apps Elo1191
Design ArenaGPT-5.1 Codex Agents Arena Webapps Elo1018
Design ArenaGPT-5.1 Codex Models Arena Code Categories Elo1151
Design ArenaGPT-5.1 Codex Models Arena Data Visualization Elo1213
Design ArenaGPT-5.1 Codex Models Arena Game Development Elo1138
Design ArenaGPT-5.1 Codex Models Arena UI Component Elo1232
Design ArenaGPT-5.1 Codex Models Arena Website Elo1160
Vals AIGPT 5.1 Codex IOI v13.7%
Vals AIGPT 5.1 Codex LiveCodeBench85.5%
Vals AIGPT 5.1 Codex Terminal-Bench 1.057.5%
Vals AIGPT 5.1 Codex Vibe Code Bench v1.113.1%

Apps

Public apps that send the most traffic to this model. Good signal for what real production workloads look like — and a hint at which use cases this model is best suited for.

Activity

Token volume and request traffic to this model over time.

API

Drop-in code to call this model. OpenRouter's API is OpenAI-compatible — most SDKs work by just swapping the base URL. The only thing that changes between models is the model slug below.

Not currently available through EU in-region routing. In-region routing docs

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Latency / throughput
$1.25$10.00$0.136.47s54 tps
99.32%
Throughput
54tok/s

P50, best across providers

Latency
6.46s

P50, best provider

Uptime (3d)The model was reachable. Request routed to a provider.
100.00%
Availability (3d)The model returned inference from any provider. Errors and empty responses count against it.
97.46%

Availability over the last 3 days

Last 72 hours
Availability 97.46%
3 Days Ago2 Days AgoYesterdayNow

Availability over the last 24 hours

OpenRouter Availability
98.13%

When an error occurs in an upstream provider, we can recover by routing to another healthy provider, if your request filters allow it. You can access per-provider uptime data programmatically through the Endpoints API. Learn more about our load balancing and provider routing options.

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Kilo Code is an open-source AI coding agent that works across VS Code, JetBrains, and CLI to help developers ship code faster with agentic workflows.
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3.
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4.
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5.
Favicon for https://roocode.com/
Roo Code
Roo Code is a VS Code extension that gives you a team of specialized AI agents with customizable modes for coding, architecture, debugging, and review, all with flexibility across any LLM or model provider.
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Frequently asked questions

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.

GPT-5.1-Codex costs $1.25/M input tokens and $10.00/M output tokens, with separate rates for Cache Read at $0.13/M tokens.

GPT-5.1-Codex has a 400,000 token context window. It supports up to 128,000 completion tokens.

Yes. GPT-5.1-Codex accepts tools and tool_choice for function calling. It also supports structured outputs via a JSON schema in response_format.

GPT-5.1-Codex accepts text and images as input and returns text.

GPT-6.1 Terra Pro, GPT-6.1 Terra, GPT-6 Luna Decisions and 62 more are other text models from OpenAI.

GPT-5.1-Codex was released on November 13, 2025.