JSON Formatter and Minifier

What is a JSON formatter?

A JSON formatter, also called a JSON beautifier or pretty printer, rewrites JSON with line breaks and indentation so a person can read it. JSON itself is a text format for objects, arrays, strings, numbers, booleans and null. Parsers ignore extra whitespace, so APIs often send everything on one long line, and a missing comma hides in the noise.

This tool pretty-prints or minifies JSON in your browser. Paste a document of up to 8 MiB.

• Indent: two spaces (the default), four spaces, or minify for a compact single line.
• Sort keys: off by default, so object key order is kept. Turn it on to sort keys recursively when you want two payloads compared without order noise.
• Duplicate object keys are rejected instead of silently keeping the last value.
• Invalid JSON is refused with the line and column of the first problem. Formatted output is capped at 18 MiB.

Why pretty-print instead of staring at one line

Minified JSON is fine on the wire and painful to review. You cannot see the nesting, you cannot tell which closing brace belongs where, and a truncated paste looks like valid JSON until something downstream fails.

Pretty-print with a stable indent and you can read the shape, copy a field, or drop the result into a diff. Minify again when you need the compact form for a request body or a config value.

Sorting keys is a separate job. Two objects that differ only in key order are equal to most programs and unequal in a text diff. Sorting makes the text match. It is not a cryptographic canonical form.

Are there alternatives?

JSON Validator on ToolkitBay is the sibling when you only need a yes or no plus a caret under the first syntax error. It uses the same parser. YAML Formatter and Validator takes the same JSON and gives it back as YAML.

jq, Python's json.tool and the format command in most editors do this work locally. Reach for those when the file is already on disk or part of a script. This page is for the JSON on your clipboard right now.

It does not check data against a JSON Schema. It only checks that the text is JSON.

Fun facts and more info

RFC 8259 allows duplicate keys, and most libraries keep the last value without telling you. That hides mistakes such as a field pasted twice, so this tool treats a duplicate as an error.

Key order follows the input unless you ask to sort. Sorted order is plain Unicode code-point order of the key strings, not the RFC 8785 JSON Canonicalization Scheme. Do not use the output as a signing input just because the keys came out sorted.

Formatting runs in your browser. The JSON is not sent to ToolkitBay's servers.