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Since May 2024: what o3 cannot know

o3 was trained on data up to May 2024. Since then, 843 models, APIs and runtimes have reached their end date and packages have shipped 367,598 breaking changes. Code it writes from memory can still use any of them.

Knowledge cutoff May 2024

On this page

The model ID is o3, from OpenAI, released April 16, 2025. The endings and the package changes below came after its training data ends, so they are not in what the model learned.

Ended since May 2024

843 models, APIs and runtimes have reached their end date since the cutoff. The newest of each:

AI models

APIs

And 807 more on the calendar.

Still ahead

450 end dates are still ahead. Some were announced after the cutoff, so the model may write what they end. The soonest of each:

AI models

APIs

And 420 more on the calendar.

Packages that changed most

Since the cutoff, package versions shipped 367,598 breaking changes, and 259,885 security advisories were published. The packages with the most breaking changes in versions released since:

  • github.com/open-policy-agent/opa Go modules, 2,907 breaking changes, newest in v1.0.0 (December 20, 2024)
  • cloudflare npm, 2,731 breaking changes, newest in 7.0.0 (July 9, 2026)
  • happy-dom npm, 2,562 breaking changes, newest in 21.0.4 (October 20, 2026)
  • skit.flurlhttpclient.wechat.api NuGet, 2,398 breaking changes, newest in 4.0.0 (November 13, 2026)
  • langfuse PyPI, 2,397 breaking changes, newest in 5.1.0 (October 30, 2026)
  • @types/three npm, 1,884 breaking changes, newest in 0.187.0 (October 30, 2026)
  • three npm, 1,884 breaking changes, newest in 0.187.0 (October 30, 2026)
  • dulwich PyPI, 1,878 breaking changes, newest in 1.0.0 (January 17, 2026)
  • github.com/envoyproxy/go-control-plane Go modules, 1,834 breaking changes, newest in v0.14.0 (November 4, 2025)
  • typescript npm, 1,818 breaking changes, newest in 7.0.2 (July 8, 2026)

Check before it writes

Run npx since-dev init in a repository and your coding agent checks a version or a model ID before it writes one, whatever model it runs on. To see what a repository already uses that has ended, scan it, or run npx since-dev inside it.

Knowledge cutoffs are from models.dev (MIT License). A cutoff given as a month is read as that month’s last day.

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Put your code on continuous maintenance.

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See how out of date your code is.

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Tell your agent what changed since it was trained.

claude mcp add --transport http since https://api.since.dev/mcp
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