Free JSON Formatter & Validator — Online, No Login
A JSON formatter takes raw, minified, or poorly structured JSON text and returns clean, indented output with consistent spacing. This tool also validates your JSON against the RFC 8259 specification and shows the exact line and character where any syntax error occurs — missing comma, unclosed bracket, wrong quote type — all in your browser, with zero data uploaded to any server.
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Format, validate, and minify JSON instantly in your browser.
- Format and beautify JSON with 2-space, 4-space, or tab indentation
- Validate JSON against the RFC 8259 specification
- Minify JSON to reduce REST API payload size
- Pinpoint syntax errors by exact line and column
- Copy formatted output to clipboard or download as .json
- Client-side processing — data is never uploaded to any server
Everything you need in one JSON Formatter
JSON validator
Every input is parsed against the RFC 8259 standard. Invalid JSON is rejected with the exact line and column of the failure, so you fix the cause instead of guessing.
JSON beautifier & pretty-printer
Turn a single-line blob into readable, indented JSON. Choose 2-space, 4-space, or tab indentation to match your project's style and make nested objects easy to scan.
JSON minifier
Strip all non-essential whitespace to reduce REST API payload size and storage cost. The data and key-value pairs are untouched — only the formatting is removed.
JSON syntax checker
Catch trailing commas, single quotes, unquoted keys, and unclosed brackets before they break your code. The status bar reports the precise position of the first error.
How to use JSON Formatter & Validator
Paste your JSON
Paste any raw, minified, or malformed JSON text into the input box. There is no size limit enforced by the UI — the browser handles the parsing.
Format or Minify
Click Format to add indentation and line breaks for readability. Click Minify to strip all whitespace, reducing payload size for APIs and storage.
Copy or download
Click Copy to clipboard for immediate use, or Download to save the output as a .json file. No account needed — results are never stored.
JSON vs common data serialization formats
| Feature | JSON | XML | YAML |
|---|---|---|---|
| REST API adoption | Universal (>90%) | Legacy systems | Rare |
| Human readability | High | Moderate | High |
| Verbosity | Low | Very high | Low |
| Comment support | No | Yes | Yes |
| Browser-native parse | JSON.parse() | DOMParser | Library required |
| Relative file size | Baseline | ~3× larger | ~1.1× larger |
| Schema validation | JSON Schema | XSD / DTD | JSON Schema / custom |
How to fix common syntax errors
Most “invalid JSON” failures come from a small set of mistakes. Paste the failing JSON above, click Validate, and the tool points you at the exact line and column.
{"a":1,}A comma after the last item in an object or array is forbidden in JSON. Remove the trailing comma.
{'name':'x'}JSON strings and keys must use double quotes. Replace single quotes with double quotes: {"name":"x"}.
{name:"x"}Every object key must be a quoted string. Change to {"name":"x"}.
{"a":[1,2}A missing ] or } usually reports an error at the end of input. Match every opening bracket with a closing one.
{a: undefined}Comments (//), NaN, undefined, and Infinity are not valid JSON values. Remove them or replace with null.
{"path":"C:\Users"}Backslashes inside strings must form a valid escape: \n, \", \\, or a Unicode escape \uXXXX.
Frequently asked questions
A JSON formatter (also called a JSON beautifier or pretty-printer) takes compact, minified, or poorly indented JSON and rewrites it with consistent indentation, line breaks, and spacing. The data structure and values are unchanged — only the whitespace is added. This makes nested objects and arrays easy to read, debug, and diff in version control.
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Further reading
Authority documentation and specifications behind this tool.
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