JSON Formatter & Validator

Paste JSON to format, minify, or validate. Error messages show exactly where the problem is.

Runs in your browser
Indent
Ctrl + Shift + F to format
Input
Output

How to Use the JSON Formatter & Validator

  1. Paste your JSON into the input area — raw, minified, or partially formatted.
  2. Click Format to pretty-print with proper indentation, or Minify to collapse it to a single line.
  3. If the JSON is invalid, an error message pinpoints the exact line and character position of the problem.
  4. Copy the formatted or minified output with one click.

About the JSON Formatter & Validator

JSON is the de facto data interchange format for web APIs, configuration files, and data storage. This tool handles the two most common JSON tasks: formatting minified or poorly indented JSON into a readable, structured form with proper indentation; and minifying pretty-printed JSON back to a compact single-line string for use in production environments or API responses. The validator uses the browser's built-in JSON.parse under the hood and surfaces meaningful error messages when syntax is invalid. All processing is local — your data never leaves the browser.

Frequently Asked Questions

Why is my JSON invalid?
Common JSON errors include: trailing commas after the last element in an array or object (not allowed in JSON), using single quotes instead of double quotes for strings, unquoted property keys, missing commas between elements, and control characters in string values. The validator will tell you the exact location of the error.
What is the difference between Format and Minify?
Format (also called pretty-print or beautify) adds indentation and line breaks to make JSON human-readable. Minify (also called compact or compress) removes all unnecessary whitespace to produce the smallest possible string representation, which is preferable for network transmission and storage.
Is there a size limit for JSON files?
There is no imposed limit — the constraint is your browser's JavaScript engine memory. JSON files up to several hundred MB can typically be processed. For very large datasets, processing may take a few seconds.
Is my data sent to a server?
No. JSON formatting and validation use the browser's native JSON.parse and JSON.stringify functions. Your data never leaves your browser and is not stored or transmitted anywhere.