What does JSON Formatter do?

It prettifies (adds readable indentation) or minifies (removes whitespace) JSON. It also validates JSON and highlights syntax errors with line numbers.

Is my JSON data sent to a server?

No. All formatting and validation runs entirely in your browser using the native JSON.parse and JSON.stringify APIs. Nothing is transmitted.

What indentation size should I use?

2 spaces is the most common convention for JSON APIs and config files. 4 spaces is common in some ecosystems. Tabs are preferred in some editors.

Can it handle large JSON files?

Yes, for files up to a few megabytes. Very large files (50MB+) may be slow because the browser parses the entire structure in memory.

What's the difference between Format and Validate?

Validate only checks if the JSON is syntactically correct and reports errors. Format also reformats the output with chosen indentation.

Can I upload a .json file?

Yes. Click the Upload button below the input box to load a .json file directly from your device.

JSON Formatter & Validator

Prettify, minify, and validate JSON instantly in your browser. Highlights errors with line numbers — nothing sent to a server.

Indent:

Input JSON

Upload .json

Output

How it works

1Paste or type your raw JSON into the input box on the left.
2Click Format to instantly prettify with proper indentation and syntax.
3Or click Minify to compact the JSON into a single line — ideal for APIs.
4Errors in the JSON are highlighted with the exact line and message.
5Copy the output with one click, or download as a .json file.
6Use Validate to check if your JSON is valid without reformatting.

Frequently asked questions

Keep going

Hash Generator

Generate MD5, SHA-1, SHA-256, SHA-512 hashes from text or files

Try now

Base64 Encoder / Decoder

Encode text or files to Base64 and decode Base64 strings instantly

Try now

JWT Decoder

Decode and inspect JWT tokens — view header, payload and expiration

Try now

URL Encoder / Decoder

Encode and decode URLs, and parse URL components including query parameters

Try now

UUID Generator

Generate UUID v1, v4 and v7 identifiers in bulk with multiple formats

Try now

Password Generator

Generate strong, random passwords with custom length and character options

Try now

HTML Entity Encoder / Decoder

Encode and decode HTML entities, plus a complete entity reference table

Try now

Text Diff Checker

Compare two texts and see differences highlighted line by line

Try now

How it works

Frequently asked questions

What does JSON Formatter do?

Is my JSON data sent to a server?

What indentation size should I use?

Can it handle large JSON files?

What's the difference between Format and Validate?

Can I upload a .json file?

Related Tools