What is a JSON formatter?

It's a tool that turns a compact or poorly formatted JSON into readable text, with indentation and line breaks, and checks whether the syntax is correct before you use the data elsewhere.

Is the JSON I paste here sent to a server?

No. All formatting, validation, and minification happen in your browser. Nothing pasted here is sent to or stored on our servers.

Why does my JSON show as invalid even though it looks correct?

The most common causes are a trailing comma before a closing brace or bracket, single quotes instead of double quotes, and an unclosed brace or bracket. The error panel shows the exact line and column so you can find the problem quickly.

Does this tool validate against a JSON Schema?

No. This tool checks whether the text is syntactically valid JSON, not whether it follows a specific schema. To validate against a JSON Schema, you need a tool built for that format.

Can I compare two JSON documents here?

No. This tool formats, validates, and minifies one JSON document at a time. To compare two documents and see the differences between them, you need a dedicated diff tool.

What's the difference between formatted and minified JSON?

Formatted JSON uses indentation and line breaks for human readability. Minified JSON strips all unnecessary whitespace, making the file smaller, which is ideal for sending over the network or shipping to production.

Does the tool handle large JSON files?

Yes, processing runs entirely in your browser and handles files of several hundred KB comfortably. For very large files, use the tree view, which renders deeper levels on demand.

Does the tool fix invalid JSON automatically?

In some cases. When the problem is a trailing comma or a comment inside the JSON, a button appears to apply the fix automatically. More structural errors, like single quotes or an unclosed brace, need a manual fix, guided by the exact location the error points to.

JSON Formatter

Format, validate, and minify JSON without leaving your browser. Syntax errors show the line, the column, and, when possible, an automatic fix.

Indentation

View

Input JSON

Result

Nothing to show yet

Paste or type a JSON on the left to see the formatted result, the tree, or any validation errors.

How to use the JSON Formatter?

Paste the JSON

Paste or type the JSON in the input field, or load the example to try the tool.

Check the result

The formatted result appears automatically on the side. If there's an error, the exact line and column are shown.

Adjust the format

Pick the indentation and switch between formatted, tree, and minified, depending on what you need.

Copy or download

Copy the result with one click or download it as a .json file.

JSON Formatter Features

Instant formatting

Paste the JSON and see the formatted result right away, with no click needed. Validation happens alongside it, in real time.

Errors with line and column

When the JSON is invalid, the reason is explained in plain language, with the line, the column, and a snippet pointing to exactly where the problem is.

Navigable tree with search

Explore nested objects and arrays in a tree you can expand and collapse, and find any key or value with the search box.

Everything in your browser

Formatting, validation, and minification all run locally. No JSON pasted here ever leaves your browser.

What is JSON?

JSON (JavaScript Object Notation) is a text format for structured data: objects with key-value pairs, lists, strings, numbers, booleans, and null. Despite the name, it doesn't depend on JavaScript. It's the standard format for REST API responses, configuration files, and data exchange between systems, with native support in practically every language.

The syntax of valid JSON

JSON accepts six value types: a double-quoted string, a number, a boolean, null, an object in braces, and an array in brackets. Object keys always use double quotes, never single quotes, and items at the same level are separated by commas, with no trailing comma after the last one.

Example of valid JSON:

{
  "name": "Ana",
  "active": true,
  "age": 30,
  "tags": ["dev", "qa"],
  "address": null
}

What devs and QAs use a JSON formatter for

Formatting and validating JSON comes up in a good part of the daily work of building and testing software:

Reading an API response that arrives as a single line, with no indentation, straight from DevTools, Postman, or Insomnia
Validating a payload before sending it, making sure the syntax is correct before debugging the logic
Inspecting test fixtures and mocks, using the tree to navigate deep structures without getting lost
Minifying a configuration file or response before committing it or sending it over the network

Common mistakes when writing JSON

Leaving a trailing comma at the end

JSON doesn't accept a comma after the last item of an object or array, unlike JavaScript. It's the most common reason for an error when pasting a JS object straight in as JSON.

Using single quotes

JSON requires double quotes for keys and strings. Single quotes, common in JavaScript objects, make the content invalid as JSON.

Leaving a brace or bracket unclosed

In large, deeply nested payloads, it's easy to lose track of open braces and brackets. The error's line and column point to exactly where a closing one is missing.

Confusing JSON with a JavaScript object

JSON doesn't accept comments, functions, undefined, or unquoted keys. A valid JavaScript object can still be invalid JSON, even when it looks identical.

Frequently Asked Questions about the JSON Formatter

Everything you need to know to format, validate, and debug JSON day to day.