What is json_serializable in Flutter?
Why Interviewers Ask This
Candidates at the intermediate level are expected to not only know this concept but explain the trade-offs involved. Interviewers use this question to see if you can reason about design decisions, not just recall facts.
Answer
json_serializable is a code generation package that automatically generates fromJson() and toJson() methods for Dart model classes. You annotate your class with @JsonSerializable() and run flutter pub run build_runner build. This eliminates hand-written boilerplate serialization code and reduces the risk of typos in JSON key strings. Combined with the json_annotation package, it supports field renaming, type converters, and null handling customization.
Pro Tip
If you're unsure about a detail, say so honestly and explain your reasoning. Interviewers respect candidates who can think through uncertainty rather than bluffing.