OpenAI: GPT-5.3-Codex
- by openai
- openai/gpt-5.3-codex
GPT-5.3-Codex is OpenAI’s most advanced agentic coding model, combining the frontier software engineering performance of GPT-5.2-Codex with the broader reasoning and professional knowledge capabilities of GPT-5.2. It achieves state-of-the-art results...
What the numbers mean
- Context window400,000 tokens
- How much the model can read in one request, counting your prompt, any files and the conversation so far. That is about 300,000 words, or 600 pages.
- Max output128,000 tokens
- The longest single reply it can write: about 96,000 words.
- Input price$1.75 per million tokens
- What you pay for everything the model reads. A 1,000-word prompt costs less than a cent.
- Output price$14 per million tokens
- What you pay for everything the model writes. Output usually costs more than input. A 500-word answer costs less than a cent.
- Modalitiestext, image, file in, text out
- The kinds of content it accepts and the kinds it produces. A model that takes images in can read a screenshot; one that only puts text out cannot draw.
Supported parameters
The settings you can pass with a request. A model that lists tools can call functions; one that lists structured_outputs can be held to a JSON schema.
include_reasoningmax_completion_tokensmax_tokensreasoningreasoning_effortresponse_formatseedstructured_outputs