Models

GPT-5.3 Codex

OpenAI · February 2026

Built for programming: writing, reviewing and fixing code, and working through long tasks on its own. Not meant for general chat.

Use instead GPT-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

    August 2025

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

Tools

  • Web searchSupported

Features

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

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