At DevDay on September 29, 2026, OpenAI said more than 35 million people use ChatGPT Work and Codex each week. That is a combined figure for two products, reported by The Decoder citing Axios. The last number OpenAI gave for Codex on its own was more than 5 million weekly active users on June 2, 2026. Codex here means the coding agent OpenAI launched in 2025 as a command line tool, a cloud agent, and later a desktop app. It is not the 2021 code model of the same name.
Codex User Timeline
| Date | Metric | Value | Source |
|---|---|---|---|
| 2025-04-16 | Launch | Codex CLI released as open source | TechCrunch, via Wikipedia |
| 2025-05-16 | Launch | Codex cloud agent in research preview | Wikipedia |
| 2026-02-02 | Monthly developers | Over 1 million, at the desktop app launch | Reuters, via Wikipedia |
| 2026-03-04 | Weekly active users | 1.6 million | Fortune, via Wikipedia |
| 2026-03-19 | Weekly active users | Over 2 million | Reuters, via Wikipedia |
| 2026-04-07 | Weekly users | 3 million | Sam Altman on X, reported by Business Today |
| 2026-04-21 | Weekly developers | Over 4 million | OpenAI, as compiled by Digital Applied |
| 2026-06-02 | Weekly active users | Over 5 million, about 20 percent knowledge workers | OpenAI report, covered by Constellation Research |
| 2026-07-09 | Product change | Codex app merged into the ChatGPT desktop app. ChatGPT Work launched | Wikipedia, GetPanto |
| 2026-07-14 | Active users | About 8 million | Press reports, compiled by BigGo Finance |
| 2026-07-21 | Active users, combined | 10 million for Codex and ChatGPT Work | OpenAI, compiled by Gradually AI |
| 2026-08-13 | Active users, combined | 15 million | BigGo Finance |
| 2026-08-21 | Active users | 20 million, no time window stated | Thibault Sottiaux, OpenAI |
| 2026-09-29 | Weekly users, combined | Over 35 million for ChatGPT Work and Codex | OpenAI at DevDay, via The Decoder |
Reading the Numbers Correctly
The series changes definition in July. Through June 2, every figure is Codex alone and weekly. After the July 9 merge with the ChatGPT desktop app, OpenAI's milestones cover Codex and ChatGPT Work together. ChatGPT Work is aimed at knowledge workers, so the 35 million figure is not a count of developers.
The 20 million figure has no stated window. Thibault Sottiaux wrote on August 21 that OpenAI had "hit 20M active users for Codex some time this week," in a post that credited every Codex and ChatGPT Work user with a usage reset. He did not say daily, weekly, or monthly.
Growth before the merge was already fast. From 1.6 million weekly users in early March to more than 5 million on June 2 is roughly a tripling in three months on a like-for-like basis. In the June report OpenAI said about one in five Codex users were knowledge workers and not developers.
Other Signals
| Signal | Value | Period | Source |
|---|---|---|---|
| npm downloads, Codex package | 88.8 million | 2026-08-31 to 2026-09-29 | npm registry API |
| npm downloads, Claude Code package | 55.8 million | 2026-08-31 to 2026-09-29 | npm registry API |
| npm downloads, Codex package | 41.8 million | May 2026 | Gradually AI, from the npm API |
| npm downloads, Codex package | 74.3 million | August 2026 | Gradually AI, from the npm API |
| Used at work by professional developers | 3% | January 2026 | JetBrains AI Pulse |
| Used at work by professional developers | 16% | May to July 2026 | JetBrains Developer Ecosystem Survey |
| Awareness among professional developers | 27% to 65% | January to mid 2026 | JetBrains |
Downloads include automated installs and updates and are not a count of people. The survey figure is the better guide to developer reach: Codex went from 3 percent to 16 percent of professional developers at work in about six months, while Claude Code stood at 39 percent in the same survey.
Plans and Access
Codex is bundled with ChatGPT plans and is not sold as a separate subscription. A DevDay recap by Learnetto lists Codex in the cloud on Plus, Pro, Business, Healthcare, Education, and Enterprise plans, with Codex Security Cloud limited to Pro, Business, Enterprise, and Edu. Gradually AI's compilation puts Plus at $20 per month, Pro from $100 per month, and Business at $25 per user per month. Third-party trackers disagree on whether the Free and Go tiers include limited Codex access, so check OpenAI's pricing page before relying on that. GPT-6.1 Sol became the default Codex model on September 29, covered in the GPT-6.1 Sol release brief and the DevDay 2026 recap.
What OpenAI Has Not Disclosed
- A Codex-only user count since June. Every later milestone combines Codex with ChatGPT Work.
- Daily or monthly active users. The published series is weekly, apart from one figure with no window.
- Codex revenue. It is not separated from ChatGPT subscription or API revenue.
- Paying versus free users. No split has been given.
- The developer share today. The 20 percent knowledge worker figure dates from June and has not been updated.
Brand Visibility Implications
- Codex picks dependencies. A coding agent that scaffolds a project chooses the database client, the email provider, and the analytics library. Each choice is a vendor recommendation that the developer often accepts unread.
- The audience now includes non-developers. With knowledge workers using Codex and ChatGPT Work to build reports and small tools, software recommendations reach people who never read developer documentation.
- Distribution rides on ChatGPT. Because Codex ships inside ChatGPT plans, its reach grows with ChatGPT's, covered in ChatGPT usage statistics.
- Measure agents separately from chat. What a model recommends in a chat answer and what it installs in a project can differ. Both need a baseline.
Methodology
This page is built from company disclosures, regulatory filings, published surveys, and press reporting, not from Presenc AI measurements. Primary sources are used wherever one exists, including Anthropic's Series G and Series H announcements, Cursor's Series D post, Mistral's Series D announcement, Alibaba's December quarter 2025 results, and the public npm download API. Survey and panel data come from JetBrains, The Pragmatic Engineer, and QuestMobile. Where a figure comes only from press coverage, such as The Decoder on OpenAI's DevDay numbers, Dealroom's summary of Forbes on Cursor, or TechNode on QuestMobile, the page says so. Company figures are self-reported and unaudited, and third-party estimates are labelled as estimates. Status as of October 1, 2026.
How Presenc AI Helps
Presenc AI tracks which brands and tools ChatGPT and other assistants recommend on the prompts your buyers use. That gives developer-facing companies a baseline for how often OpenAI's models name them when a product choice is being made.