DEV · JSON & API

JSON Formatter & Validator

Paste any JSON, then pretty print or minify it in one click. Instantly validate your JSON and see helpful error messages with the exact line and column so you can debug faster.

  • Format messy JSON into readable, indented structure.
  • Minify JSON by removing extra whitespace for smaller payloads.
  • Validate JSON syntax and see where the error happens (line & column).
  • Quickly copy formatted JSON into your code editor, API client, or docs.

Everything runs in your browser. Your JSON is not uploaded to any server, so it’s safe to use with internal API responses, configs, or application data.

Input JSON
Paste any JSON. Then choose whether you want to pretty print or minify, and click “Format & validate JSON”.
Formatting options
Formats JSON with indentation and new lines for easier reading.
Removes line breaks and extra spaces for smaller payloads.

Result & validation status

JSON validation
Waiting for input…
Paste JSON and click “Format & validate JSON”
No validation performed yet Mode: pretty print (default)
Input characters
0
Total characters in the raw JSON
Result characters
0
Characters after formatting
Input lines
0
Lines in the original JSON
Result lines
0
Lines after formatting
Paste your JSON on the left, choose Pretty or Minify, then click “Format & validate JSON” to see the result and validation status here.

What does the JSON Formatter & Validator do?

The JSON Formatter & Validator helps you clean up and verify JSON used in APIs, configuration files, and application data. You can paste any JSON, then pretty print it for readability or minify it for compact size while checking whether the syntax is valid.

When your JSON is valid, the tool formats it according to the selected mode. If there’s a syntax error, you’ll see a clear message with the character position and an estimated line and column so you know exactly where to look.

How JSON validation works

When you click “Format & validate JSON”, the tool:

  • Reads the text from the input textarea.
  • Runs a JSON parse to check if the syntax is valid.
  • If valid, it formats the JSON using the mode you selected: pretty print (multi-line) or minify (single-line).
  • If invalid, it shows an error message with the character index and an estimated line and column number to help you fix the issue.

The summary box on the right shows whether the JSON is valid, how many characters and lines you started with, and how many remain after formatting.

Pretty vs minified JSON

Pretty printed JSON is formatted with indentation and new lines, making it easier for humans to read and review. This is ideal when debugging API responses, inspecting payloads, or sharing examples with your team.

Minified JSON removes unnecessary whitespace and line breaks. This is useful when you need a smaller payload for production, want to embed JSON in HTML/JS, or send compact data over the network.

When to use this tool

The JSON Formatter & Validator is especially useful when you:

  • Debug API responses coming from REST or GraphQL endpoints.
  • Check JSON configs before deploying them to production.
  • Validate request payloads copied from browser dev tools or logging output.
  • Clean up JSON snippets before adding them to documentation or tutorials.

Tips for best results

  • Make sure your JSON is valid JSON, not JavaScript. Remove comments, trailing commas, and single quotes, as they’re not valid in strict JSON.
  • Use Pretty print for debugging, then switch to Minify when you’re ready to send the data in production.
  • Copy the formatted output with the “Copy result” button to quickly reuse JSON in your editor or API client.
  • Use “Swap input & result” to run another pass or change from Pretty to Minify (or the other way around) without pasting again.

Use this tool whenever you need a quick, browser-based way to format and validate JSON for your APIs, configs, or application data.