JSON Validator
Paste JSON. Get a coloured verdict — green Valid with key / depth stats, or red Invalid with first error highlighted. The error panel includes line, column, a snippet of the offending line, and a one-sentence explanation of what's wrong. Auto-fix the entire document with json-repair.
Paste JSON to validate.
How to validate JSON
- Paste your JSON.
- The verdict appears in a coloured banner: green = Valid with key / depth stats, red = Invalid with first error.
- For invalid input, the error panel lists every error: line, column, snippet, and a one-sentence explanation ("trailing comma after the last array item", "unquoted key", "missing closing brace").
- Jump to error scrolls the input to the failing line.
What invalid JSON looks like
- Trailing comma:
[1, 2, 3,]— remove the comma before]. - Single quotes:
{'name': 'Alice'}— use double quotes. - Unquoted key:
{name: "Alice"}— wrapnamein double quotes. - JS comments:
// noteor/* ... */— JSON disallows them. - Trailing data: two JSON values separated only by whitespace — wrap in an array or use NDJSON.
FAQ
What spec does this validate against?
RFC 8259, the current JSON standard. Same rules as JSON.parse in browsers and Node, and json.loads in Python's stdlib.
What about JSON5 / JSONC?
This validator is strict JSON only. For JSON5 (comments, unquoted keys, trailing commas) and JSONC (JSON with comments), json-repair can convert most inputs to strict JSON.
Does it validate against a schema?
No — for schema validation use json-schema-validator. This tool only checks well-formedness.
Will it work offline?
Yes — it uses the browser's built-in JSON.parse.