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Model usage data, product updates, and research reports. One email each week.

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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. Higher percentages are better — and rank percentile shows where this model lands among all models on OpenRouter.

Benchmark score summary for OpenAI: GPT-5.1-Codex (Artificial Analysis and Design Arena)
SourceBenchmarkScore
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) Terminal-Bench Hard34.8%
Artificial AnalysisGPT-5.1 Codex (high) AA-Omniscience Accuracy39.9%
Artificial AnalysisGPT-5.1 Codex (high) AA-Omniscience Non-Hallucination Rate22.8%
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 Elo1033
Design ArenaGPT-5.1 Codex Models Arena Code Categories Elo1167
Design ArenaGPT-5.1 Codex Models Arena Data Visualization Elo1228
Design ArenaGPT-5.1 Codex Models Arena Game Development Elo1161
Design ArenaGPT-5.1 Codex Models Arena UI Component Elo1252
Design ArenaGPT-5.1 Codex Models Arena Website Elo1174

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.

Quick Start

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.

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$1.25$10.00$0.137.22s63 tps
100.00%

Throughput

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P50, best across providers

Latency

7.22s

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.

99.95%

Availability over the last 3 days

Last 72 hours
Availability 99.95%
3 Days Ago2 Days AgoYesterdayNow

Availability over the last 24 hours

OpenRouter Availability
99.85%

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 customization options.

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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 Astra, GPT-6 Astra Pro, GPT-5.6 Luna Pro and 55 more are other text models from OpenAI.

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

More models from OpenAI

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GPT Terra Latest

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GPT Luna Latest

This model always redirects to the latest model in the GPT Luna family.

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GPT Image 2.5 Sunburst

GPT Image 2.5 Sunburst is an image generation and editing model from OpenAI, positioned as the precision-oriented tier of the GPT Image 2.5 series. It is suited to detailed creative work where editing accuracy matters more than generation speed, via the dedicated Images API.

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GPT Image 2.5 Flare

GPT Image 2.5 Flare is an image generation and editing model from OpenAI, positioned as the speed-oriented tier of the GPT Image 2.5 series. It is suited to high-volume everyday generation, creator content, and rapid prototyping via the dedicated Images API.

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GPT-6 Astra

GPT-6 Astra is OpenAI's flagship model for demanding end-to-end work. It is suited for advanced analysis, software engineering, deep research, scientific work, and document creation, with particular strengths in long-horizon agentic tasks that involve computer and browser use.

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GPT-6 Astra

GPT-6 Astra is OpenAI's flagship model for demanding end-to-end work. It is suited for advanced analysis, software engineering, deep research, scientific work, and document creation, with particular strengths in long-horizon agentic tasks that involve computer and browser use.

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GPT-6 Astra Pro

GPT-6 Astra Pro is the same underlying model as GPT-6 Astra, served with reasoning.mode set to pro for higher-quality responses on complex tasks.

Learn more in OpenAI's docs: https://developers.openai.com/api/docs/guides/reasoning#reasoning-mode

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GPT-6 Astra Pro

GPT-6 Astra Pro is the same underlying model as GPT-6 Astra, served with reasoning.mode set to pro for higher-quality responses on complex tasks.

Learn more in OpenAI's docs: https://developers.openai.com/api/docs/guides/reasoning#reasoning-mode

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GPT Transcribe

GPT Transcribe is a high-accuracy speech-to-text model from OpenAI. It is suited for recorded audio, streamed file transcription, and committed Realtime turns, with free-form context, keyword hints, and multiple language hints for specialized terms and multilingual speech.

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GPT-5.6 Luna Pro

GPT-5.6 Luna Pro is the same underlying model as GPT-5.6 Luna, served with reasoning.mode set to pro for higher-quality responses on complex tasks.

Learn more in OpenAI's docs: https://developers.openai.com/api/docs/guides/reasoning#reasoning-mode

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GPT-5.6 Luna Pro

GPT-5.6 Luna Pro is the same underlying model as GPT-5.6 Luna, served with reasoning.mode set to pro for higher-quality responses on complex tasks.

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GPT-5.6 Luna

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GPT-5.6 Luna

GPT-5.6 Luna is a fast, cost-efficient model in OpenAI's GPT-5.6 series. It is suited for high-volume, latency-sensitive tasks such as chat, classification, and lightweight agentic workflows, providing capable reasoning for its price tier.

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GPT-5.6 Terra Pro

GPT-5.6 Terra Pro is the same underlying model as GPT-5.6 Terra, served with reasoning.mode set to pro for higher-quality responses on complex tasks.

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GPT-5.6 Terra Pro

GPT-5.6 Terra Pro is the same underlying model as GPT-5.6 Terra, served with reasoning.mode set to pro for higher-quality responses on complex tasks.

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GPT-5.6 Terra

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GPT-5.6 Terra

GPT-5.6 Terra is a balanced model in OpenAI's GPT-5.6 series, positioned between the flagship Sol tier and the cost-efficient Luna tier. It is suited for everyday coding, reasoning, and agentic tasks where capability and cost need to be balanced, offering strong performance at roughly half the cost of Sol.

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GPT-5.6 Sol Pro

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Learn more in OpenAI's docs: https://developers.openai.com/api/docs/guides/reasoning#reasoning-mode

Text1.1M context$2 / $10