JSON formatter.
Paste JSON to instantly pretty-print with 2 or 4-space indent, or minify it. Clear syntax errors with line and column. All local.
Tool 10DeveloperLive100% local
§ Valid or not
Strict, quiet, helpful.
Formatting uses the browser’s own JSON parser, so if it validates here, it validates in production.
Why does my perfectly-valid-looking JSON fail?
JSON is strict: no trailing commas, no comments, keys must be double-quoted strings, and the root must be an object or array. Paste it into this tool to see exactly where the parser gives up.
Does it preserve key order?
Yes. Both Pretty and Minify keep the original insertion order; JSON.stringify does not re-sort.
How big a payload can it handle?
Browsers can parse multi-megabyte JSON happily. Very large payloads (10MB+) may briefly freeze the UI while parsing — that is a limitation of the main thread, not the tool.