How to format and validate JSON in your browser
A formatter makes nested JSON easier to read. A validator tells you whether the text is valid JSON syntax. Those are useful checks, but they do not prove that an API accepts the data.
Updated 5 October 2026. The related tool processes pasted text in your browser.
Format JSON in three steps
- Open the JSON formatter and validator and paste up to 1 MiB of JSON text.
- Choose Format to add two-space indentation, or choose Validate to check syntax without changing the input.
- Choose Minify for a compact one-line result, review it and copy it if needed.
The text is parsed in your browser. It is not uploaded or saved by the tool, and no account is required.
How to read a parse error
The browser's JSON parser may report a character position. The tool converts that position into a best-effort line and column. Start there, then inspect the surrounding structure.
- Property names need double quotes.
- Items need commas between them, but not after the final item.
- Every opening brace or bracket needs a matching closing character.
- JSON uses
true,falseandnullas values. It does not use JavaScript comments.
Syntax is not schema validation
Valid JSON can still have the wrong fields, types or values for a particular API. This tool does not read a JSON Schema, repair input, sort keys or predict whether another service will accept the result.
After formatting, compare the field names and value types with the receiving service's documentation. Keep the original input until you have checked the result.
Privacy and limits
The formatter accepts up to 1 MiB of pasted text and processes it in the browser. The JSON text is not sent to Firm Beacon or saved by the tool. Normal page requests and anonymous analytics still occur when the page loads. Analytics can record action names, not the JSON content.
JSON formatting questions
Does formatting validate JSON?
Yes. The tool must parse the input before formatting or minifying it. Validate checks the same JSON syntax without changing the input.
What does a JSON parse error mean?
It means the browser could not parse the text as standard JSON. Check the reported location and look for missing commas, unclosed brackets, trailing commas or unquoted keys.
Is this schema validation?
No. The tool checks JSON syntax only. It does not compare the data with a JSON Schema or confirm that an API will accept it.