Does my JSON get uploaded to a server?

Not for processing. Formatting runs in your browser with JavaScript's built-in JSON parser, with no server-side step.

Why does it say my JSON is invalid when it looks fine?

The most common causes are trailing commas after the last item in an object or array, single-quoted strings instead of double quotes, or an unquoted object key — all valid in JavaScript object literals but not in strict JSON. The error message includes the line and column where parsing failed.

What's the difference between formatting and minifying?

Formatting adds indentation and line breaks to make JSON human-readable. Minifying strips all non-essential whitespace to produce the smallest possible payload — useful before sending JSON over a network or storing it.

Is there a file size limit?

There's no hard limit enforced by the tool, but very large files (tens of megabytes) may feel slow since parsing happens on your device's main thread. For typical API responses and config files this is instant.

Can I format JSON with comments in it?

No — comments aren't part of the JSON specification, so standards-compliant JSON can't contain them. If your input is actually JSONC (JSON with Comments) or JSON5, strip the comments first or use a JSON5-aware tool.

Does my JSON get uploaded to a server?

Not for processing. Formatting runs in your browser with JavaScript's built-in JSON parser, with no server-side step.

Why does it say my JSON is invalid when it looks fine?

The most common causes are trailing commas after the last item in an object or array, single-quoted strings instead of double quotes, or an unquoted object key — all valid in JavaScript object literals but not in strict JSON. The error message includes the line and column where parsing failed.

What's the difference between formatting and minifying?

Formatting adds indentation and line breaks to make JSON human-readable. Minifying strips all non-essential whitespace to produce the smallest possible payload — useful before sending JSON over a network or storing it.

Is there a file size limit?

There's no hard limit enforced by the tool, but very large files (tens of megabytes) may feel slow since parsing happens on your device's main thread. For typical API responses and config files this is instant.

Can I format JSON with comments in it?

No — comments aren't part of the JSON specification, so standards-compliant JSON can't contain them. If your input is actually JSONC (JSON with Comments) or JSON5, strip the comments first or use a JSON5-aware tool.

JSON Formatter

Format, validate, and minify JSON instantly in your browser, no signup.

JSON input

Loading editor…

Formatted JSON

Indent:

Enter JSON on the left to format it.

What is JSON Formatter?

JSON (JavaScript Object Notation) is a lightweight, text-based data interchange format defined in RFC 8259 that uses human-readable structures of objects and arrays to represent data. A JSON formatter parses raw or minified JSON and re-emits it with consistent indentation and line breaks so the structure is easy to read and mistakes are easy to spot. Because it uses a strict parser, it also surfaces syntax errors — trailing commas, single-quoted strings, and unquoted keys are valid in JavaScript object literals but rejected by JSON — with the exact line and column where parsing failed. The same operation can minify the input, stripping all non-essential whitespace to produce the smallest possible payload for network transfer.

How to use JSON Formatter

Paste or type your raw JSON into the input box on the left — or drag a .json file straight onto it.
Choose an indent width (2 or 4 spaces, or a tab) from the dropdown.
The formatted, syntax-validated output appears instantly on the right — no button click needed.
Click "Copy" to copy the formatted JSON, or switch to "Minify" mode to collapse it to a single line.

Examples

Compact to pretty

Input

{"name":"Ada","active":true,"roles":["admin","user"]}

Output

{ "name": "Ada", "active": true, "roles": [ "admin", "user" ] }

Nested objects

Input

{"user":{"id":1,"address":{"city":"Berlin"}}}

Output

{ "user": { "id": 1, "address": { "city": "Berlin" } } }

Minify mode

Input

{ "a": 1, "b": 2 }

Output

{"a":1,"b":2}

Common mistakes

Leaving a trailing comma after the last property in an object or the last item in an array — valid in JavaScript, invalid in JSON.
Using single quotes ('like this') instead of double quotes ("like this") for strings and keys.
Forgetting to quote object keys — JSON requires every key to be a double-quoted string, unlike JavaScript object literals.
Mixing up JSON with JSONC/JSON5 (which allow comments and trailing commas) and expecting a strict JSON parser to accept them.

Why use this tool

Formats in your browser, with no server-side step.
Instant feedback with precise line/column error reporting, rather than a generic "invalid JSON" message.
No installation, account, or rate limit — unlike CLI tools (jq) or IDE-only formatters, it works from any device with a browser.
Combines formatting, minifying, and validation in one tool instead of three separate utilities.