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Since September 2023: what GPT-4o mini cannot know

GPT-4o mini was trained on data up to September 2023. Since then, 985 models, APIs and runtimes have reached their end date and packages have shipped 397,746 breaking changes. Code it writes from memory can still use any of them.

Knowledge cutoff September 2023

On this page

The model ID is gpt-4o-mini, from OpenAI, released July 18, 2024. The endings and the package changes below came after its training data ends, so they are not in what the model learned.

Ended since September 2023

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

AI models

APIs

And 949 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 397,746 breaking changes, and 265,324 security advisories were published. The packages with the most breaking changes in versions released since:

  • date-fns npm, 3,983 breaking changes, newest in 4.0.0 (September 16, 2024)
  • 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)
  • doctrine/orm Packagist, 2,480 breaking changes, newest in 3.0.0 (February 3, 2024)
  • 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)
  • typo3/cms-core Packagist, 1,892 breaking changes, newest in v14.0.0 (November 25, 2025)
  • @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)

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