Format, validate and diff JSON
Paste JSON to validate it (errors show line and column), reformat it, or paste a second document to diff their structures. The original digits of every number are kept as written.
Structure diff
How to use it
- Paste JSON — validity, size and any error position appear immediately.
- Format, minify or sort keys; copy or download the result.
- For a comparison, paste a second document and review the changed paths.
Limits & formats
Up to 2 MB of text. The formatter is a strict JSON parser (one value, no comments, no trailing commas) that preserves each number's original literal — numbers beyond the 15-17 significant digits doubles can represent, or outside the safe integer range, are kept exactly and flagged with a warning instead of being silently rounded. The diff compares structure (object keys, array lengths, value types) line by line; it is a developer aid, not a semantic guarantee.
Privacy
Everything is computed locally in this browser tab; nothing is sent or stored.
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