"JSON formatter" and "JSON validator" get used almost interchangeably, but they're answering two different questions: is this readable, and is this actually correct. A single tool that does both — format when it's valid, explain exactly where it breaks when it isn't — is more useful than either alone.
Steps
- Open JSON Formatter and paste your JSON.
- Choose Pretty-print (readable, indented) or Minify (compact, one line) as the output mode.
- Run it — valid JSON is formatted instantly; invalid JSON shows a specific parse error instead of a silent failure.
Formatting: making valid JSON readable
Minified JSON from an API response or a build tool is correct but unreadable — everything on one line, no spacing. Pretty-printing re-indents it (2 spaces, 4 spaces, or a tab, your choice) so nested objects and arrays are visually obvious. Minifying does the reverse: it strips all that whitespace back out, which is what you want before actually sending JSON over the wire, since every space is a byte you don't need to transmit.
Validating: catching what's actually broken
Formatting only works on JSON that's already valid — feed it a trailing comma, an unquoted key, or a stray single-quote instead of double-quotes, and a real parser has to reject it rather than guess what you meant. That rejection is the validation: the error message names what went wrong (unexpected token, unterminated string, and so on), which is usually enough to find the exact character that needs fixing, rather than manually scanning a wall of text for a missing brace.
Why you need both, not just one
A formatter that silently "fixes" broken JSON by guessing your intent can mask a real bug — the kind that only shows up later as a confusing error somewhere else in a pipeline. A validator with no formatting still leaves you staring at unreadable minified output once it does pass. Together, one pass does both jobs: confirms the JSON is actually correct, and makes it readable if it is.