OpenAI's Codex has surpassed 15 million users, according to @kimmonismus on X. The milestone signals a reset in AI coding assistants, with Codex leading the pack.
Key facts
- Codex surpassed 15 million users, per @kimmonismus
- GitHub Copilot had 20 million users in early 2025
- OpenAI reported $4 billion revenue in late 2024
- Codex available via ChatGPT Plus, Pro, and API tiers
- OpenAI has not commented on the 15 million figure
OpenAI's Codex coding assistant has crossed the 15 million user mark, according to a tweet from @kimmonismus per @kimmonismus. The figure, which the account describes as "another reset," underscores Codex's rapid growth since its public launch in 2025.
The 15 million number is notable for several reasons. First, it positions Codex well ahead of competing AI coding tools like GitHub Copilot, which had around 20 million users as of early 2025 but has since faced stiffer competition. Second, the milestone suggests Codex has moved beyond early adopters into mainstream developer workflows, a shift that could pressure other players in the space.
What the number means
While the tweet does not break down the user base, the figure likely includes free-tier users who may not convert to paid plans. OpenAI has not officially commented on the 15 million figure, and the company did not disclose how many of those users are active or paying. Still, the scale is significant: Codex's growth trajectory mirrors that of ChatGPT, which hit 100 million weekly users in late 2023, but in a more specialized domain.
Codex's rise comes amid a broader "reset" in AI coding tools, as agents like Codex, Claude Code, and others shift from autocomplete to autonomous task execution. This user milestone is a signal that developers are embracing these agents, not just as helpers but as core parts of their toolchain.
Competitive pressure
The 15 million user count puts Codex in direct competition with GitHub Copilot, which reported 20 million users in early 2025 but has since seen slower growth as new entrants emerge. Anthropic's Claude Code, for instance, has gained traction among enterprise developers, though its user numbers are not public. The milestone also raises questions about monetization: Codex is available via ChatGPT Plus, Pro, and API tiers, but the free tier likely drives much of the user count.
OpenAI has not disclosed Codex-specific revenue or paid conversion rates, so it is unclear how many of those 15 million users are paying customers. The company's broader AI revenue, reported at $4 billion in late 2024, suggests Codex is a meaningful contributor, but the exact split remains opaque.
What to watch
Watch for OpenAI's next earnings disclosure or product announcement that reveals Codex's paid user count or revenue contribution. Also track whether GitHub Copilot responds with new features or pricing changes to counter Codex's momentum. A shift in user growth from free to paid tiers would be the key metric to confirm Codex's commercial viability beyond the headline number.
