Format and Validate JSON

The JSON developers most need to format is almost always the JSON they should be most careful with — an API response mid-debugging, a config file, a webhook body. It routinely contains bearer tokens, API keys, internal hostnames, and real customer records. Pasting that into a random tool means pasting it into someone else's server logs. This formatter parses and re-serialises entirely in the page, so the payload stays in the tab and disappears when you close it.

Prettify re-indents valid JSON for reading; minify strips whitespace for transport. Invalid JSON is reported with the parser error rather than a vague failure. In practice the culprit is one of a small handful of things: a trailing comma after the last item, single quotes instead of double, an unquoted key, or an unescaped newline inside a string. All four are legal in a JavaScript object literal and illegal in JSON, which is exactly why they slip through.

This is a formatter and syntax validator, deliberately kept simple. It does not do JSON Schema validation, JSONPath queries, side-by-side diffing, or conversion to YAML and CSV. If you need those, dedicated JSON editors cover them well. If you want to indent a payload and find the syntax error without an ad blocker fight, you are in the right place.

That is the promise behind every tool here. Files are read in your browser tab, processed there, and discarded when you close it — never uploaded to our servers.