Content and text
JSON Formatter and Validator
Format, minify or check JSON and see exactly where it breaks.
Runs in your browser; nothing is uploaded. · Free, no account · 1 min
Importing a saved run into your account is coming soon. Until then, your last runs stay in this browser only, and you can download your files.
How to use
- Paste your JSON into the box, or load the example.
- Choose Format, Minify or Validate only, and the indent you prefer.
- Switch to JSONC mode if the file has comments or trailing commas.
- Fix any error at the line and column shown, then copy or download the result.
What it checks and how it works
Strict mode follows RFC 8259: keys and strings in double quotes, no comments, no trailing commas. The tool parses with jsonc-parser, the parser behind the JSON support in Visual Studio Code, so each error comes with a line and a column. JSONC mode accepts comments and trailing commas, as VS Code's JSON with Comments mode does. Sort keys is optional and orders object keys alphabetically at every depth.
It does not repair broken JSON or guess what you meant. Formatting rewrites numbers through JavaScript, so a number beyond 2^53 or with more than 17 significant digits is flagged: it may lose digits in the output.
Sources
- RFC 8259: The JavaScript Object Notation (JSON) Data Interchange Format opened 29 Oct 2026
- Visual Studio Code: JSON with Comments (jsonc) mode opened 29 Oct 2026
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Questions
About this tool
Code often accepts what RFC 8259 does not: single quotes, unquoted keys, comments or a trailing comma. Strict mode points to each one, and JSONC mode accepts comments and trailing commas.
No. The JSON is parsed and formatted inside your browser, so it works with private payloads and nothing is uploaded.
Yes. Strings keep their characters exactly, and the tool does not turn them into escape sequences.
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