Backend
API Versioning
Also written as Breaking Changes, Backward Compatibility
Managing changes to an API without breaking the apps and customers that already use it, usually by running old and new versions side by side (/v1, /v2) until everyone has moved.
Think of it like
Opening a new motorway junction while keeping the old exit open until drivers have learned the new route.
Junior or senior?
A good signal of having owned a public or widely used API.
Senior sounds like
Talks about deprecation timelines and how they got clients to migrate.
Ask them
“How did you roll out a breaking change without breaking existing clients?”