Model dossier

OpenAI: GPT-5.1-Codex-Max

GPT-5.1-Codex-Max is OpenAI’s latest agentic coding model, designed for long-running, high-context software development tasks. It is based on an updated version of the 5.1 reasoning stack and trained on agentic...

ProviderOpenAI Start comparison

Context400,000

Max output128,000

Pricing viewTVP price

Identity

OpenAI: GPT-5.1-Codex-Max

Model ID: openai/gpt-5.1-codex-max
Canonical slug: openai/gpt-5.1-codex-max-20251204
Knowledge cutoff: n/a
Created: 12/4/2025

Capabilities

textimagetoolsstructured

Modalities

text+image->texttextimage

Capacity

Context400,000

Max output128,000

TokenizerGPT