Debug JSON duplicate keys in API responses
Duplicate keys are technically allowed by RFC 7159, but most parsers keep only the last value. Silent merges and mismatches between client and server are common. Diffing two snapshots helps you spot accidental duplication.
Common causes
- Merged configs or hand-edited JSON.
- Multiple sources writing the same object.
- Logging and re-serializing without deduplication.
How to fix
- Prefer JSON Diff to compare two captures side by side.
- Enforce a single key per name in generators.
- Add schema validation in CI for critical responses.
Use our tool
Compare JSONRelated