JSON Formatter & Validator: format, minify, and debug JSON fast

JSON is the duct tape of modern software. It powers APIs, configuration files, log payloads, and event pipelines. And yet a single missing quote or trailing comma can turn a simple task into a frustrating debugging session.

This guide shows you how to validate JSON, fix the most common errors, and format or minify JSON safely. If you just want to get unstuck quickly, you can jump straight to the tool here: JSON Formatter & Validator.

What a JSON formatter and validator does

A formatter takes valid JSON and outputs it in a readable layout (often called “pretty JSON”) with indentation and line breaks. A validator checks whether your input is valid JSON and provides an error message when it isn’t.

In practice, you use the combination to (1) confirm validity, (2) locate the error, and (3) standardize output so diffs and reviews are easier.

Common JSON errors (and how to fix them)

1) Trailing commas

JSON is stricter than JavaScript. This is invalid JSON:

{
  "a": 1,
}

Fix: remove the trailing comma.

2) Single quotes instead of double quotes

JSON requires double quotes for strings and keys:

{ 'a': 'b' }

Fix: use double quotes:

{ "a": "b" }

3) Comments

JSON doesn’t allow comments. If you need comments, consider JSONC (JSON with comments) for internal config, but remember it’s not standard JSON.

4) Unescaped characters

Newlines inside strings must be escaped. If you’re pasting content, the validator will catch it.

Pretty vs minified JSON

• Pretty JSON is best for humans: debugging, documentation, and code review.
• Minified JSON removes whitespace. It can be useful for compact payloads or storing JSON in places where size matters.

Tips for working with large JSON

• Validate first. If it’s invalid, formatting won’t help.
• Format it, then search for the key you care about.
• Prefer stable key ordering in your generating systems when possible (JSON itself doesn’t guarantee order).

Privacy note

Our JSON tool runs in your browser. That means your input stays on your device (unless you paste it elsewhere). Still, avoid sharing secrets in screenshots.

Use the tool

Ready? Open the tool here: JSON Formatter & Validator.