JSON Formatter

Format, validate, and minify JSON data. Advanced JSON formatter with syntax highlighting, error detection, and multiple output formats.

JSON Formatter & Validator
Format, validate, and minify JSON data with advanced options
Input JSON
Paste your JSON data here
Formatted Output
Formatted and validated JSON

Formatted JSON will appear here

Enter JSON and click Format

JSON Formatter Features

What We Do

  • • Format and beautify JSON data
  • • Validate JSON syntax
  • • Minify JSON for production
  • • Customizable indentation
  • • Error detection and reporting
  • • Copy and download results

Use Cases

  • • API response debugging
  • • Configuration file formatting
  • • Data structure visualization
  • • Code review preparation
  • • JSON schema validation
  • • Data transformation

JSON validation vs. JSON formatting — what you need and when

Validation checks if a string is syntactically valid JSON. Formatting reorganizes valid JSON with consistent indentation and newlines. You need both: a file can be valid but unreadable, or formatted-looking but contain a syntax error that breaks parsing.

Your API returns a 200 with a body that looks like JSON, but your client throws a parse error. Common culprits: a trailing comma after the last array element, a single-quoted string instead of double-quoted, or a BOM character at the start of the file. Paste the raw response here and the validator pinpoints the exact error — line number, character position, and what was expected.

Minifying JSON for production — how much size does it actually save?

Minifying JSON removes whitespace, newlines, and indentation without changing the data. For large API responses with deeply nested objects, minification can reduce payload size by 15–30%, directly improving API response times.

A config file with 4-space indentation and 500 lines becomes 120 lines minified — and gzip compression works better on the minified version because repeating patterns compress more efficiently. Use minified JSON for production API responses and data files. Use formatted JSON for config files, documentation, and code reviews where humans need to read and edit the content.

Common JSON syntax errors that look correct but break parsing

The five most common JSON errors: trailing commas after the last item in an array or object (valid in JavaScript, invalid in JSON), single-quoted strings (JSON requires double quotes), undefined or NaN values (not valid — use null), comments (JSON has no comment syntax), and integer keys (JSON keys must be strings). This formatter catches all of them and reports the position.

Using the JSON formatter as part of an API debugging workflow

Copy the raw response body from Postman, curl output, or browser DevTools, paste it here, and immediately see if it's valid, where the error is, and what the structure looks like — without needing a local environment.

When debugging API integrations, the bottleneck is often just reading the response. A minified 2KB JSON blob on one line is unreadable. Format it here and you can immediately see whether the nested object is missing a field, whether an array has the expected number of items, or whether a date field is a string or a number. Download the formatted version to share with your team or attach to a bug report.

Format and validate your JSONFormat and validate your JSON