JSON formatter and validator for readable output and syntax checks. Choose indentation, format or minify the input, and review any parser error.
The JSON Formatter turns minified or unevenly formatted JSON into indented output. Use the JSON validator to check syntax, or minify valid JSON for a compact version.
Paste an API response, configuration snippet, or export, then choose the operation you need. A syntax check does not verify that the data matches your application schema.
Formatting adds indentation and line breaks. Minifying removes unnecessary whitespace. Validation checks whether the input can be parsed as JSON and reports an error when it cannot.
Format / beautify: pretty-prints with 2, 4, or 8 space indentation to show nested objects and arrays.
Minify: collapses formatted JSON into a single line with all unnecessary whitespace removed, for a compact representation of the parsed JSON.
Validate: checks the input for valid JSON syntax. If something is wrong, you get the parser's error message verbatim (e.g. Unexpected token } in JSON at position 142), which can help locate the problem. Error wording and detail can vary by browser.
One-click copy: the output area has a copy button that places the result on your clipboard for pasting into your IDE, terminal, or message thread.
Clear: resets input, output, and any error state so you can start a new check without page reload.
Auto-focus on input: the input textarea is focused when the page loads, so you can paste and act immediately.
Parsing and serialization: uses the native JSON.parse and JSON.stringify APIs. Review the values after formatting, especially large numeric identifiers.
Paste your raw JSON into the "Input JSON" textarea. Large inputs can use substantial browser memory; keep a copy of the source.
Choose the indentation from the dropdown: 2, 4, or 8 spaces. Match the style used by your project.
Click Format for a beautified version, Minify for a single-line version, or Validate for a quick syntax check that simply confirms "Valid JSON".
If your input has a syntax error, you'll see a red error banner with the exact parser message. Edit your input and try again: no need to clear first.
Click the copy button next to the output to put the result on your clipboard.
Format an API response before reading nested fields, or inspect a browser localStorage dump. Check configuration files such as values.json and keep an original copy before changing their values.
Pretty-print expected and actual payloads with the same indentation to make a comparison easier. The formatter does not decide which values are correct.
JSON is a strict, well-defined format. The official specification (RFC 8259) allows exactly six value types: object ({ ... }), array ([ ... ]), string (UTF-8, double-quoted), number (integer or floating-point, no leading zeros except for the digit zero itself, no NaN or Infinity), boolean (true / false), and null. Object keys must be double-quoted strings. Trailing commas are not allowed (a frequent JavaScript-vs-JSON pitfall). Comments are not part of the spec, so a JSON document that contains // or /* */ will fail to parse: even though many config-file dialects (JSON5, JSONC, HuJSON) extend JSON to support them. If your input includes such extensions, strip the comments before formatting, or switch to a tool built for that dialect.
JavaScript cannot represent every integer at and above 2^53 exactly. The safe-integer upper limit is 9,007,199,254,740,991. For 64-bit integer IDs, use strings when the receiving system expects an exact value. Keep the original input and compare important numbers after formatting.
Match the indentation used in your project. For very large files, consider a streaming parser such as JSONStream in Node or ijson in Python rather than loading the whole document into this page.
Use snake_case or camelCase consistently when designing field names. Check the application schema separately: valid JSON can still have missing fields or unexpected value types.
The formatting operations use JavaScript's JSON object. Follow your organization's handling requirements before entering tokens, customer information, or confidential exports into a web tool.
Save the source before formatting. Review values as well as indentation, and check the expected schema separately before using the result in an application.
How to Use JSON Formatter and Validator - Format and Minify JSON
Paste the source into Input JSON. Keep an original copy, especially if it contains large numeric identifiers.
Choose indentation and click Format for readable output, Minify for compact output, or Validate for a syntax check.
If parsing fails, read the error, correct the input, and try again. A syntax pass does not confirm that the data matches your application schema.
Review the values and copy the result. Compare important identifiers and numbers with the original before using the formatted data.
JSON formatter and validator for readable output and syntax checks. Choose indentation, format or minify the input, and review any parser error.
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Apr 30, 2026Type:
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