When was OpenAI GPT-5.3 Codex released?

OpenAI GPT-5.3 Codex was released on 2026-02-05.

What is the context window of GPT-5.3 Codex?

GPT-5.3 Codex supports a context window of 400K tokens.

GPT-5.3 Codex pricing is $1.25 per 1M input tokens and $10.00 per 1M output tokens.

GPT-5.3 Codex is available via API Only on OpenAI API, Azure OpenAI, GitHub Copilot.

Major Release OpenAI Code Proprietary

Name: OpenAI GPT-5.3 Codex
Availability: API Only
Author: OpenAI

Coding-specialized variant of GPT-5.3, tuned for agentic IDE workflows.

Released 2026-02-05 · ~200B · 400K tokens context · knowledge cutoff 2025-11

OpenAI's specialized self-improving coding model with state-of-the-art software engineering performance

DeveloperOpenAI

Release date2026-02-05

Model typeCode

Parameters~200B

ArchitectureMoE (coding-specialized fine-tune)

Context window400K tokens

Max output100K

Knowledge cutoff2025-11

LicenseProprietary

Input modalitiestext, image

Output modalitiestext

Benchmark	GPT-5.3 Codex	GPT-5.2 Codex	Δ
Terminal-Bench	77.3%	72.8%	+4.5
SWE-Bench Pro	SOTA	—	—
Speed	1,000+ tok/s	—	—
SWE-bench Verified	82.4%	78.2%	+4.2
HumanEval	96.8%	95.1%	+1.7
LiveCodeBench	84.2%	80.4%	+3.8
Aider Polyglot	79.5%	—	—

$1.25

per 1M input tokens

$10.00

per 1M output tokens

$0.13

per 1M cached input tokens

API Only OpenAI API Azure OpenAI GitHub Copilot

Direct comparison available in the model comparison tool →