📄JSON Formatter / Validator

How to Use

1. 1

   Paste your JSON

   Click Paste to paste from clipboard, or type JSON directly in the input area. A sample is available to try the tool immediately.

2. 2

   Choose a mode

   Select Format to prettify the JSON with readable indentation, or Minify to compress it into a single line.

3. 3

   Adjust indentation

   In Format mode, choose 2 spaces, 4 spaces, or Tab as the indentation style.

4. 4

   Check validation and copy

   A green indicator confirms valid JSON. If the JSON is invalid, the error message shows what went wrong. Copy the output with the Copy button.

FAQ

How do I expand / prettify a single-line JSON?

Paste your JSON into the input area and click Format. The tool instantly expands it into a human-readable multi-line format. Choose 2 spaces, 4 spaces, or Tab indentation to match your style. This works great for API responses, curl output, or any minified JSON.

My JSON shows an error. What are the most common causes?

The most common JSON errors are: (1) trailing commas after the last array/object item (e.g. ,] or ,}), (2) strings in single quotes instead of double quotes, (3) unquoted property keys, (4) mismatched or missing brackets/braces, and (5) JavaScript-only values like undefined or NaN. The validator shows the exact error message to help you fix it.

Can I paste an API response or curl output directly?

Yes. Paste the raw response body from any REST API, browser DevTools Network tab, curl output, or Postman and click Format. If the API returns a double-encoded JSON string (a JSON string wrapped in extra quotes), strip the outer quotes first.

What is JSON and where is it used?

JSON (JavaScript Object Notation) is the most widely used data interchange format on the web. It represents data as key-value pairs (objects) and ordered lists (arrays). You'll find JSON everywhere: REST API responses, config files like package.json, browser localStorage, and more. Its simplicity and readability make it the de facto standard for data exchange between clients and servers.

Does it support JSON with comments (JSONC) or JSON5?

No. This tool validates standard JSON (RFC 8259) only. Comments (// or /* */), trailing commas, and single-quoted strings used in JSON5 and JSONC will cause validation errors. If you need to format a file like VS Code's settings.json, remove the comments before pasting.