A third of public API specs vanished, half of surviving contracts changed

An apis.guru study re-fetched 1,927 public OpenAPI/Swagger specs from 2023 in September 2026: 27% of URLs now return 404/410 while 63.8% still work. Among surviving contracts, 48.9% changed and 66.8% of those changes were breaking, yet 88.8% kept the same major version.

• 27% of 1,927 spec URLs return 404 or 410, another 6.3% don't respond
• 48.9% of surviving contracts changed in three years, 66.8% of changes breaking
• Endpoint removed in 45.3% of breaking specs, response field removed in 44.1%
• 88.8% of breaking changes shipped without a major version bump