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JSON formatter & validator.

Pretty-print, minify, validate, or convert JSON to YAML or XML. Errors are pinpointed by line and column.

Paste or type JSON above

sort keys

Try an example: simple object array of objects nested has an error

How it works

Validation uses native JSON.parse; pretty-printing and minification use native JSON.stringify. YAML conversion uses js-yaml, loaded once from a CDN. XML conversion is a small built-in serializer. The four output tabs share one parser pass — flipping between them doesn't re-parse, so output is instant even on large payloads.

Pure browser, no server. The pasted JSON never leaves the page.

Common gotchas

Trailing commas — strict JSON disallows them, even inside arrays and objects.
Single quotes — keys and string values must use double quotes.
Unquoted keys — JavaScript object literals allow them; JSON does not.
Comments — JSON has none. Use JSON5 or YAML if you need them.

Planned

JSON5 input — accept trailing commas and comments without erroring.
JSON Path / jq-style query — paste a payload, type a path, get the value.
Schema inference — paste an example object, get a TypeScript type or JSON Schema definition.

v0.1 · 2026