How to use the JSON formatter
- Paste your JSON into the input box — an API response, config file or log line.
- Pick an output style: 2 or 4 spaces, tabs, or minified. Optionally sort object keys alphabetically.
- The output updates instantly. If the JSON is invalid, you'll see the exact error with its line and column.
- Copy the result, or feed it back in as input to keep editing.
Private by design
Many online formatters send your data to their servers. This one doesn't — parsing and formatting happen entirely in your browser using the native JSON.parse and JSON.stringify. It's safe to paste production payloads, access tokens or customer records.
Common JSON syntax errors and fixes
| Error | Invalid | Valid |
|---|---|---|
| Trailing comma | {"a": 1,} | {"a": 1} |
| Single quotes | {'a': 'x'} | {"a": "x"} |
| Unquoted key | {a: 1} | {"a": 1} |
| Comments | {"a": 1 // note} | Remove the comment |
| Special values | {"a": NaN} | {"a": null} |
JSON data types
Valid JSON supports exactly six value types: strings (double-quoted), numbers, booleans (true/false), null, arrays and objects. Dates, undefined, functions and comments are not part of the standard (RFC 8259) — dates are conventionally stored as ISO 8601 strings.
When to minify vs. beautify
Beautified JSON is for humans: reading API responses, reviewing config changes, debugging. Minified JSON is for machines: it shrinks payloads by removing whitespace, which reduces bandwidth for APIs and storage. Most web servers also gzip responses, so minification matters most for stored data and very large payloads.
Working with encoded payloads? Try the Base64 decoder or inspect tokens with the JWT decoder.
Frequently asked questions
Is my JSON sent to a server?
No. Formatting and validation run entirely in your browser using JavaScript's built-in JSON parser. Your data never leaves your device, so it's safe for API responses containing tokens or personal data.
Why is my JSON invalid?
The most common causes are trailing commas, single quotes instead of double quotes, unquoted keys, comments (not allowed in standard JSON), and special values like NaN or undefined. The validator shows the line and column of the first error.
What's the difference between beautify and minify?
Beautify adds indentation and line breaks to make JSON readable. Minify removes all unnecessary whitespace to make the payload as small as possible for network transfer or storage.
Does sorting keys change my data?
No. JSON object key order carries no meaning, so sorting keys alphabetically produces an equivalent document. It's handy for comparing two JSON files or producing stable diffs. Array order is never changed.
Last updated: 22 September 2026Suggest an improvement · Report a problem