CEZAMJSON formatter
Indent, validate, minify.
Paste your JSON; it is validated as you type and never leaves your browser.
- 100% local — your data never leaves your browser
- Free, no usage limits
- No sign-up, no account
How it works
Paste a JSON document: it is validated continuously as you type. “Format” rewrites it with two-space indentation, “Minify” strips every optional whitespace. Once an action is chosen, the output follows your edits without re-clicking, along with its exact UTF-8 byte size and a copy button.
On a syntax error, the tool shows the engine’s message plus the line:column position, recomputed from the exact error index. Everything runs in your browser: nothing is ever sent to any server.
Limits
The error position depends on the browser: Chrome, Edge and Firefox provide it, Safari may only give the message. Columns are counted in UTF-16 units, as JavaScript engines do — an emoji therefore counts as two.
Reformatting goes through the native JSON parser: duplicate keys collapse to their last value and numbers are rewritten in canonical form (1.50 becomes 1.5, integers beyond 2⁵³ lose precision). On documents of several tens of MB, rendering may pause briefly.