JSON Formatter & Validator

Format and validate JSON instantly

The JSON Formatter & Validator takes messy, minified, or hand-written JSON and turns it into clean, properly indented, readable structure — or compresses it back down to a single line. At the same time it validates your JSON and reports the exact error if something is wrong, so you can fix it fast. Everything happens in your browser, which means your data is never uploaded and the formatting is instant even for large payloads.

What is JSON?

JSON (JavaScript Object Notation) is the most widely used data format for APIs, configuration files, and data exchange between systems. It is lightweight, human-readable, and supported by virtually every programming language. But JSON is also strict: a single missing comma, an extra trailing comma, or an unquoted key will make the whole document invalid. That is exactly where a formatter and validator saves you time.

How to use the JSON formatter

1. Paste your JSON into the editor above.
2. Click Format to beautify it with clean two-space indentation, or Minify to strip all whitespace.
3. If the JSON is invalid, you will see a clear error message describing the problem.
4. Click Copy to grab the result, or Clear to start over.

Format vs minify — when to use each

Action	Result	Use when
Format (beautify)	Indented, multi-line, readable	Debugging, reading API responses, code review
Minify	Single line, no spaces	Reducing payload size for production and storage

Common JSON errors and how to fix them

• Trailing commas — JSON does not allow a comma after the last item in an object or array.
• Unquoted keys — every key must be wrapped in double quotes.
• Single quotes — JSON requires double quotes, not single quotes.
• Missing brackets — every { and [ needs a matching close.
• Comments — standard JSON does not support comments; remove them.

When you click Format, the validator parses your text with the same engine browsers use, so the error message you see is precise and trustworthy.

Private by design

Many JSON tools send your data to a server to process it. This one does not. All parsing, formatting, and validation run locally in your browser, so even sensitive API responses, tokens, and customer data never leave your machine. That makes it safe to use at work and on confidential projects.

Tips for working with JSON

Keep your JSON formatted while developing so structure is obvious at a glance, then minify before shipping to reduce size. When an API returns an error, paste the response here to spot malformed fields quickly. And if you are writing config by hand, format frequently to catch a stray comma before it breaks your build.