GPT-5-Codex in the API
GPT-5-Codex is now available in the Responses API, and you can also use it with your API Key in the Codex CLI.
OpenAI changelog: September 2025
2 releases from to
Everything OpenAI shipped in September 2025, collected from official OpenAI sources. Each entry is dated and links to the page it came from.
September 2025 at a glance
September 2025 was OpenAI's busiest month of the 12 months to then: 2 releases, about 4× its monthly average of 1. That was the same number as in August 2025. Every release this month was Model.
Releases
2
+0 vs August 2025
Rank of 12 months
1st
Average 0.5 a month
Most shipped
Model
2 releases
Notable OpenAI launches in September 2025
- Model
GPT-5-Codex in the API
GPT-5-Codex is now available in the Responses API, and you can also use it with your API Key in the Codex CLI.
Source: Codex Changelog - Model
GPT-5-Codex
GPT-5-Codex is a version of GPT-5 further optimized for agentic coding in Codex, available in the IDE extension and CLI with ChatGPT sign-in. It also adds image outputs for front-end tasks in the cloud, codex resume and automatic context compaction in the CLI.
Source: Codex Changelog
All OpenAI releases in September 2025
Newest first. Each entry links to the official page it came from.
September 20252 releases
GPT-5-Codex
GPT-5-Codex is a version of GPT-5 further optimized for agentic coding in Codex, available in the IDE extension and CLI with ChatGPT sign-in. It also adds image outputs for front-end tasks in the cloud, codex resume and automatic context compaction in the CLI.
Where September 2025 sits
OpenAI releases per month, for September 2025 and the 11 months before it. A taller bar means more releases that month; the dated entries for each month are on its own page.
Other companies in September 2025
8 of the companies we track shipped in September 2025; OpenAI ranks 6th by number of releases.
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