GPT-5.3 Codex is OpenAI's most capable agentic coding model, combining frontier software engineering performance with broad reasoning capabilities. 25% faster than GPT-5.2 with state-of-the-art SWE-Bench Pro results and strong terminal proficiency.
- Most capable agentic coding model combining frontier software engineering with broad reasoning.
- 400,000-token context window with 128,000 max output tokens and reasoning effort support (low, medium, high, xhigh).
- 25% faster than GPT-5.2 with state-of-the-art performance on SWE-Bench Pro benchmarks.
- Strong terminal proficiency and real-world computer-use skills for complex development workflows.
- Pricing is $1.75 per 1M input tokens and $14 per 1M output tokens (cached input at $0.175).
Model Information
Supported Formats
GPT 5.5OpenAI's most advanced model released April 2026. GPT-5.5 is recommended for most reasoning workloads, combining frontier intelligence with configurable reasoning effort (none → xhigh). Available in API, Codex, and ChatGPT.
GPT 5.5 ProHighest-intelligence API option in the GPT-5.5 family. Use for the most challenging problems that require maximum reasoning depth and can tolerate higher latency. Supports full reasoning effort range from none to xhigh.
GPT 5.4GPT-5.4 is OpenAI's frontier model for complex professional work, designed for agentic, coding, and professional workflows with the highest reasoning capability. Features a 1.05M token context window, native computer use, and built-in support for web search, file search, and MCP.