JSON formatter / validator

About this JSON formatter

A JSON formatter is the tool you reach for when an API returns one giant line of compact JSON, when a config file refuses to load because of an invisible syntax error, or when you need to embed JSON somewhere with character limits. This formatter does all three jobs — pretty-print, minify, validate — in your browser, without uploading anything anywhere.

Most online JSON tools route your data through their servers, which is fine for public data but a non-starter for anything sensitive (API responses with customer info, internal config, payloads with auth tokens). This one uses your browser's native JSON.parse and JSON.stringify, so your data never leaves the device. Open DevTools and watch the Network tab — no requests fire when you paste or format.

Common questions

Is this JSON formatter safe for sensitive data?

Yes. The entire tool runs in your browser using native JSON.parse and JSON.stringify. Nothing gets sent to a server, nothing is logged, nothing is stored. You can use it offline once the page loads.

What does pretty-print do?

Pretty-print reformats JSON with line breaks and indentation so it is human-readable. The result is the same JSON, just easier to scan — useful when an API returns one long line of compact JSON.

What does minify do?

Minify removes all whitespace from your JSON so the result is the smallest possible string. Useful for embedding JSON in URLs, reducing payload size, or storing it in places with character limits.

What does validate do?

Validate runs JSON.parse and reports any syntax errors with their line and column. Useful for finding the trailing comma, unquoted key, or unescaped character that is breaking a config file or API request.

Why does this not need a signup?

Because there is nothing to track, store, or limit — the math runs in your browser. Moonshot offers signup-required tools elsewhere (saved sessions, cross-sheet operations) but this one does not need it.