OpenAI: GPT-5 Codex✓ Catalog verified
GPT-5-Codex is a specialized version of GPT-5 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, 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.
Overview
GPT-5-Codex is a specialized version of GPT-5 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, 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.
Access: available through the official OpenAI API. Context window: 400K.
Specifications
| API identifier | openai/gpt-5-codex |
| Provider | OpenAI |
| Model type | Multimodal LLM |
| Context window | 400K catalog |
| Input modalities | text · image |
| Output modalities | text |
| Released | Sep 23, 2025 |
| Tokenizer | GPT |
| Moderated | Yes |
| Architecture modality | text+image->text |
API defaults
{
"top_p": null,
"temperature": null,
"frequency_penalty": null
}Pricing
Live pricing components for openai/gpt-5-codex as published in the catalog.
| Pricing component | Raw unit price | Normalized | Unit |
|---|---|---|---|
| Prompt tokens | $0.00000125 | $1.25 / 1M | Per input token |
| Completion tokens | $0.00001 | $10.00 / 1M | Per output token |
| Request fee | N/A | N/A | Per request |
| Image fee | N/A | N/A | Per image unit |
| Web search fee | N/A | N/A | Per search request |
Cost calculator
Estimate monthly spend from your own token volumes.
Estimated Total Cost
$2.63Calculated from current list pricing in the ModelsAtlas catalog.Capabilities
| Capability | Status | What it means |
|---|---|---|
| Visual Understanding | ✓ Supported | Image and document analysis support |
| Audio Processing | Not advertised | Speech and voice aligned flows |
| Tool Calling | ✓ Supported | Supports tools / function calling |
| Self-Hosting | Not advertised | Deploy outside managed APIs |
Capability signals
Directional signals derived from model metadata and capability tags — not official benchmark submissions.
Quick start
Call OpenAI: GPT-5 Codex through an OpenAI-compatible client.
from openai import OpenAI
client = OpenAI(
base_url="https://openrouter.ai/api/v1",
api_key="YOUR_API_KEY"
)
response = client.chat.completions.create(
model="openai/gpt-5-codex",
messages=[{"role": "user", "content": "Explain quantum physics."}]
)
print(response.choices[0].message.content)Alternatives
Closest models by context window from a different provider.
| Model | Provider | Context | Input /1M | Actions |
|---|---|---|---|---|
| Meta: Llama 4 Scout | Meta | 328K | $0.08 | View → |
| Amazon: Nova Lite 1.0 | Amazon | 300K | $0.06 | View → |
Head-to-head comparisons
Side-by-side breakdowns of OpenAI: GPT-5 Codex against other frontier models.
Sources & attribution
Pricing and metadata are maintained in the ModelsAtlas catalog.
Frequently asked questions
How much does OpenAI: GPT-5 Codex cost?
$1.25 per 1M input tokens and $10.00 per 1M output tokens on the official OpenAI API.
What is the context window of OpenAI: GPT-5 Codex?
OpenAI: GPT-5 Codex supports up to 400K tokens of context.
Does OpenAI: GPT-5 Codex support tool / function calling?
Yes, OpenAI: GPT-5 Codex supports tool / function calling — you can register tools and the model will emit structured tool calls.
How do I access OpenAI: GPT-5 Codex?
Use the official OpenAI API with the model id `openai/gpt-5-codex`. See the Quick start section above for code examples.