Models

GPT-5.1 Codex Max

OpenAI · December 2025

Built for programming tasks that run a long time on their own.

Use instead GPT-5.6 Sol →

  • Modalities

  • Context window

    400,000 tokens, ≈ 300,000 words · about 1,200 pages

  • Max output

    128,000 tokens, ≈ 96,000 words in a single answer

  • Knowledge cutoff

    September 2024

Reasoning effort

  • Low

  • Medium

  • High

  • X-High

Providers

Files you can attach

  • ImagesJPG, PNG, GIF, WEBP
  • DocumentsPDF, DOCX, XLSX, PPTX
  • Text and codeTXT, MD, CSV, TSV, RPT, LOG, PY, TS, TSX, JS, JSX, CS, GO, JAVA, KT, SWIFT, CPP, C, H, PHP, RB, SQL, SH, PS1, HTML, CSS, SCSS, JSON, YAML, YML, XML, INI

Features

  • StreamingSupported
  • Function callingSupported
  • Structured outputsSupported
  • Fine-tuningNot supported

Ready to try it?

Log in

Bring your own API key · Your chats stay in your browser