How does Auto-Fix repair trailing commas and single quotes?
Our tokenizer safely scans outside string literals to remove trailing commas before `}` or `]` and normalizes single quotes into valid double quotes.
JSON Validator & Syntax Checker
Pinpoint exact line and column syntax errors and auto-repair broken JSON payloads.
Pinpoint Exact Line & Column Syntax Errors
When `JSON.parse` fails, our diagnostic engine calculates the exact line number, column offset, and offending token—highlighting the error directly in the editor.
One-Click Auto-Fix for Broken JSON
Use the "Auto-Fix JSON" button to automatically strip trailing commas, convert single-quoted keys/strings to double quotes, and strip JavaScript comments.
Most Common JSON Syntax Mistakes
Learn how to spot unescaped control characters, missing closing braces, and invalid `undefined` or `NaN` literals that break strict RFC 8259 parsers.
Frequently Asked Questions
What is RFC 8259 JSON compliance?
RFC 8259 is the official IETF standard requiring UTF-8 encoding, double-quoted property names, and strict primitive types (string, number, boolean, null, object, array).
Are comments allowed in standard JSON?
Standard JSON forbids `//` or `/* */` comments. Our Auto-Fix tool strips comments so your payload passes strict validation.