JSON Formatter & Validator - Pretty Print JSON Online

How to Format JSON Online

Paste your JSON data into the input field above, then click Format to pretty-print it with your chosen indentation level (2 spaces, 4 spaces, or tabs). Click Minify to compress it to a single line. The tool validates your JSON syntax and shows clear error messages if anything is wrong.

This JSON formatter handles all valid JSON data types: objects, arrays, strings, numbers, booleans, and null values. It correctly processes deeply nested structures, Unicode characters, and escaped sequences.

Common JSON Formatting Use Cases

  • API debugging — format compressed API responses to inspect the data structure
  • Configuration files — beautify JSON config files for readability and version control
  • Database records — format MongoDB documents, CouchDB records, or JSON columns
  • Log analysis — pretty-print JSON log entries to find errors quickly
  • Code reviews — format JSON fixtures and test data for easier review

Understanding JSON Syntax Rules

Valid JSON must follow these rules:

  • Keys must be strings wrapped in double quotes ("key", not key or 'key')
  • Strings use double quotes only ("value", not 'value')
  • No trailing commas after the last item in an object or array
  • No comments — JSON does not support // or /* */ comments
  • Numbers cannot have leading zeros — use 0.5, not .5 or 00.5

If you need to convert your JSON to a different format, try our JSON to YAML converter or CSV to JSON converter.

Features

  • Format and minify — toggle between readable and compact JSON
  • Syntax validation — catch errors before they reach production
  • Configurable indentation — 2 spaces, 4 spaces, or tabs
  • One-click copy — copy the result to your clipboard
  • Client-side only — your data never leaves your browser

Looking for more developer utilities? Check out our Base64 encoder/decoder, URL encoder/decoder, or regex tester. For working with structured data schemas, try the JSON Schema Builder.

Frequently Asked Questions

What is JSON formatting?

JSON formatting (also called pretty printing) is the process of adding proper indentation, line breaks, and spacing to a compressed JSON string to make it human-readable. A JSON formatter transforms a single-line string like {"name":"John","age":30} into a structured, indented format that is easy to read and debug.

How do I validate JSON online?

Paste your JSON into the input field above and click Format. If the JSON contains syntax errors, the tool will display a clear error message pointing to the issue. Valid JSON will be formatted with proper indentation. Common errors include missing commas, unquoted keys, trailing commas, and single quotes instead of double quotes.

Is my data safe when using this JSON formatter?

Yes, completely safe. This tool runs 100% in your browser using JavaScript. Your JSON data is never sent to any server, never stored, and never logged. When you close the page, all data is gone. This makes it safe to format sensitive configuration files, API keys, and private data.

What is the difference between JSON formatting and minifying?

Formatting adds whitespace and indentation to make JSON readable by humans. Minifying removes all unnecessary whitespace to create the smallest possible string, which is ideal for network transfer, API responses, and storage where file size matters. Both operations preserve the data structure and values.