JSON formatter and validator
Fix broken payloads and read API responses without sending them to a server.
Valid JSON: object, 3 top-level keys, nesting depth 3, 114 bytes (114 minified).
Formatted
{
"service": "api",
"checks": [
{
"name": "db",
"ok": true
},
{
"name": "cache",
"ok": false,
"latencyMs": 812
}
],
"version": "2.4.1"
}Minified
{"service":"api","checks":[{"name":"db","ok":true},{"name":"cache","ok":false,"latencyMs":812}],"version":"2.4.1"}Assert on JSON fields in API responses with transaction monitors. Free for 5 monitors, no credit card.
Start monitoringHow it measures
- Parsing uses the browser's JSON.parse, so the result matches what JavaScript clients accept (RFC 8259).
- When parsing fails, a small validating scanner locates the first error, since browsers no longer report positions.
Limits
- Comments, trailing commas and single quotes are invalid JSON and reported as errors, by design.
- Very large documents (tens of megabytes) may be slow in the browser.
Troubleshooting
- Unexpected token at a line that looks fine
- Look at the previous line: a missing comma or an unclosed string is reported where the parser first notices it.