Articles
Notes on API compatibility
What breaks the users of a library, how often it happens and how to catch it before a release.
Article · 10 November 2026
Seven Kotlin changes that pass your build and break your users
A default argument, a renamed parameter, a moved file, a new data class property: what happens to callers, and what to do instead. Each one checked with Kotlin 2.2.20.
Article · 10 November 2026Seven Java changes that pass your build and break your users
A wider parameter, a new interface method, a final class: changes that compile and pass the tests, what happens to callers, and the compatible alternative. Each one checked on Java 25.
Report · 10 November 2026How often does a “compatible” release break its users?
We replayed 1,201 recent minor and patch releases of the most-used Maven Central libraries: about 1 in 8 contains a breaking change. Our data, the published studies and their limits.