Why APIs break

Seedling

May 1, 2025 1 min read

APIs tend to break for organizational reasons as much as technical ones:

Skipped versioning - a breaking change ships on the same endpoint and every existing client breaks at once.
No contract enforcement - without a shared schema, the two sides drift until a deploy surfaces the mismatch.
Ignored backward compatibility - removing a field or tightening validation breaks callers even when the happy path still works.

Under all three sits coordination: an API is a boundary between teams, so most breakages are really a communication failure at that boundary.