JSON Formatter

About the JSON Formatter

The JSON Formatter turns compact or messy JSON into clean, indented text you can actually read. Paste a minified API response, a configuration file or a webhook payload, and it is re-printed instantly with consistent indentation, one property per line and nested objects clearly lined up. If the JSON has a mistake, you get the line and column of the problem instead of a vague “invalid” message.

Developers use it while debugging APIs, testers to inspect responses, students to learn how JSON is structured, and technical writers to prepare examples for documentation. Because it runs entirely in your browser, you can format responses that contain customer data or access tokens without sending them to a server.

What is JSON, and what does formatting do?

JSON (JavaScript Object Notation) is a plain-text format for structured data, defined in the standard RFC 8259. It is built from objects (key–value pairs in curly braces), arrays (ordered lists in square brackets), strings in double quotes, numbers, true, false and null. Almost every web API, mobile app and modern configuration system exchanges data as JSON.

To save bandwidth, servers usually send JSON minified, with all spaces and line breaks removed. That is efficient for machines but hard for people to read. Formatting, also called beautifying or pretty-printing, parses the JSON and writes it out again with line breaks and indentation, without changing any data. Formatting also acts as a check: if the text cannot be parsed, it is not valid JSON, and the formatter tells you where the problem is.

How to use the JSON Formatter

1. Paste your JSON into the JSON input box, or click Try example to load a sample.
2. Choose the Indentation: 2 spaces, 4 spaces or tabs.
3. Tick Sort keys A–Z if you want object keys in alphabetical order at every level.
4. Read the message above the output: “Valid JSON” with the number of top-level keys or array items, or an error with its line and column.
5. Use Copy result to copy the formatted JSON, or Download to save it as formatted.json. Reset clears both boxes.

Formatting runs automatically as you paste or edit, so you can fix an error in the input and watch the output appear as soon as the JSON becomes valid.

Key features and benefits

• Instant formatting. Output updates as you type or paste, with no button to press
• Three indentation styles. 2 spaces, 4 spaces or tabs to match your project’s code style
• Precise error messages. Line and column numbers, plus hints for the most common mistakes such as single quotes and trailing commas
• Key sorting. Sorts object keys alphabetically at every depth, making two JSON documents much easier to compare
• Structure summary. Confirms the JSON is valid and shows how many top-level keys or array items it has
• Copy and download. Copy the result or save it as a .json file
• Private. Uses your browser’s built-in JSON parser; nothing is uploaded or executed

Practical examples

Minified API response

Input: {"id":7,"name":"Ali","roles":["admin","editor"],"active":true}. With 2-space indentation the output puts each key on its own line, lists the two roles on separate lines inside the array, and the message reads “Valid JSON · 4 top-level keys”.

Trailing comma error

Input: {"city":"Lahore","zip":54000,}. The formatter reports the position of the error and adds: “Tip: trailing commas are not allowed in JSON.” Remove the last comma and the formatted output appears.

Single quotes from JavaScript

Input copied from JavaScript code: {'name': 'VIPTools'}. JSON requires double quotes, so the formatter reports an error at the first single quote and suggests using double quotes around strings and keys.

Comparing two configurations

Two settings files contain the same keys in different orders. Format each with Sort keys A–Z ticked, then compare them with the Text Diff Checker: only the real differences remain.

Quick reference: JSON value types

Every value in a JSON document is one of six types. When the formatter reports an error, it is usually because a value is written in a way that is not one of these:

Common use cases

• Web and mobile developers read API responses, webhook payloads and log entries while debugging.
• QA testers inspect responses and check that required fields are present.
• DevOps engineers tidy JSON configuration files before committing them.
• Students learn how nested objects and arrays fit together.
• Technical writers prepare readable JSON examples for documentation and tutorials.

Accuracy, limitations and privacy

Parsing uses the browser’s native JSON.parse, which follows the JSON standard strictly, and output is produced by JSON.stringify, so the data itself never changes, only its layout. Exact error wording differs slightly between Chrome, Firefox and Safari, because each browser writes its own parser messages; the line and column are calculated from them.

The JSON is processed as text in your browser. It is never uploaded, stored or executed, so formatting is safe even for private data. Very large files of many megabytes may take a moment on older phones.

• Comments, trailing commas, single quotes and unquoted keys are not valid JSON. They are allowed in JSON5 or JSONC, which this tool does not accept.
• Numbers larger than JavaScript’s safe integer range (about 9 quadrillion) may lose precision when re-printed.
• Duplicate keys in one object are collapsed; only the last value is kept, as in most JSON parsers.

Tips and best practices

• If an API response starts with HTML such as <!DOCTYPE, the server returned an error page, not JSON.
• Use 2-space indentation for web projects and 4 spaces where your team’s style guide asks for it.
• Sort keys only for reading and comparing; some systems care about key order in signatures or hashes.
• Remove secrets such as API keys before sharing formatted JSON in tickets or chats.
• To send JSON compactly again, run the formatted output through the JSON Minifier.

Related tools and next steps

To check JSON and see its depth and size, use the JSON Validator; to shrink it for production, use the JSON Minifier. Compare two formatted files with the Text Diff Checker. If an API returns Base64-encoded fields, decode them with the Base64 Decoder, and convert Unix timestamps inside JSON with the Unix Timestamp Converter.