Reviewed 2026-08-28
How to Validate JSON and Diagnose Parse Errors
Turn a vague parse failure into a precise, reproducible correction.
Example input
{"name":"Ada","roles":["admin",]}Expected output
Invalid JSON: trailing comma before ]
Reproducible method
- Preserve the original and create the smallest representative sample.
- Run a strict parse or validation before transformation.
- Record options, compare counts and structure, then test in the receiving system.
Common error
The reported location can appear after the token that caused the failure.
Reduce a failure while retaining the problematic structure; this separates malformed input from unsupported behavior.
Technical limitation
Syntax validity does not prove schema or business validity.
A successful preview does not remove format ambiguity or downstream requirements.
Security and privacy
Keep the original unchanged and never paste production secrets.
Local processing reduces transfer risk but cannot protect a compromised browser, unsafe extensions, clipboard history, or later misuse.
Verification checklist
- Check field, record, page, or byte counts.
- Review edge cases and error output.
- Retain the original until acceptance.
- Document assumptions for automation.