What is the context window of Codex 1?

Codex 1 has a context window of 192K tokens.

When was Codex 1 released?

Codex 1 was released on 2025-05-16.

What benchmarks has Codex 1 been tested on?

Codex 1 has been evaluated on 1 benchmark, including SWE-bench Verified.

Codex 1

Name: Codex 1
Author: OpenAI

codex-1

DeprecatedResearched 143d ago

Last refreshed 2026-04-18. Next refresh: weekly.

ProprietaryCodingAgentsLong context

Codex 1 is a legacy integration reference; keep it only while you identify a current replacement.
Decision context: Coding task fit, 0 tracked provider routes, and research from 2026-01-01.

Use it for

Teams maintaining an existing integration
Workloads that can use a 192K context window

Do not use it for

New production launches
Cost-sensitive launches that need sourced token pricing
Vision or document-understanding workloads

Cheapest output

No tracked output price

Provider routes

No provider route in seed

Quality / dollar

Unknown

No output-token price in the ladder

Freshness

2026-01-01

Researched 143d ago

stale

This API model is marked deprecated. Verify the replacement path before sending new production traffic.

Top use-case fit

Coding

1 relevant benchmark in the decision map.

Agents

1 relevant benchmark in the decision map.

Long context

Included by capability and metadata signals in the decision map.

Provider price ladder

No tracked provider token pricing is available for this model yet.

Benchmark peer barsfor Coding

SWE-bench VerifiedRank 36 of 52

Claude Mythos Preview

93.9

87.6

85.0

82.6

72.1

Migration checks

No linked migration route is available for this model yet.

About

OpenAI's primary Codex model for software engineering, built on o3 architecture. Trained via reinforcement learning on real-world coding tasks. Features sandboxed container execution, GitHub PR export, diff review, and multi-file reasoning. Default model for the OpenAI Codex cloud coding agent, available on Plus, Pro, Business, and Enterprise tiers.

Codex 1 has a 192K-token context window.

Capabilities

ReasoningCode Execution

Benchmark Scores(1)

Scores are benchmark-specific and are direction-aware: the same numeric gap can mean very different outcomes across suites. Use the leaderboard context and this model's provider route to decide whether the winning margin is meaningful for your workload.