Overview
Paste JSON that fails to parse and this tool attempts to automatically fix the mistakes that cause most real-world JSON errors: trailing commas before a closing brace or bracket, single quotes used instead of double quotes, unquoted object keys (valid in JavaScript object literals but not JSON), JavaScript-style comments (// and /* */) left in from hand-editing, and missing commas between properties or array items. Unlike json-formatter, which only validates and pretty-prints already-valid JSON, this tool actively rewrites the input to fix it - and shows exactly which fixes were applied in a plain summary below the result, so nothing changes silently without you knowing what happened. If the input has an issue too significant to safely guess at - a genuinely mismatched bracket, a truncated value - the tool reports a clear parse error instead of producing a guessed, possibly-wrong result. Runs entirely client-side.
Best for: Fixing a hand-edited config file or JS-object-literal-turned-JSON that won't parse
How to use this tool
- Paste the broken JSON. Trailing commas, single quotes, unquoted keys, comments, or missing commas - any combination is fine.
- Fixes are applied automatically. Each category of mistake is checked and corrected in turn.
- Read the "what was fixed" summary. A plain list shows exactly which categories of fix were applied - nothing changes invisibly.
- Copy the repaired JSON. The result is pretty-printed and re-validated before it's shown as successful.
Why use this tool
Fixes five common mistake categories
Trailing commas, single quotes, unquoted keys, JS comments, and missing commas - the ones that actually happen.
Transparent about what changed
A visible summary lists every category of fix applied, instead of silently rewriting your input.
Never guesses wrong silently
The repaired output is re-validated with a real JSON parse before being shown - if it still doesn't parse, you get an error, not broken output.
Different job than the formatter
json-formatter validates and pretty-prints already-valid JSON; this tool is specifically for JSON that doesn't parse yet.
Frequently asked questions
The JSON Formatter validates and pretty-prints JSON that's already syntactically correct - if it's not valid, that tool just reports the parse error and stops. This tool is specifically for JSON that fails to parse: it actively rewrites the input to fix common mistakes (trailing commas, single quotes, unquoted keys, comments, missing commas) and only shows a result once the fixed version successfully parses as valid JSON.
After applying every available fix, the tool always re-validates the result with a real JSON.parse - if that still fails (for example, because of a genuinely mismatched bracket or a value cut off mid-string), you get a clear parse error instead of a guessed and possibly-wrong output. The tool is deliberately built to fail loudly rather than silently produce incorrect JSON.
No - the repair logic tracks which parts of the input are inside a string literal versus structural JSON syntax, so fixes like comment removal and quote normalization are only applied outside of string content. A slash inside a string value, for example, is never mistaken for the start of a comment.