JSON Formatter & Validator

JSON is the data format most APIs speak. Format it for reading, minify it for sending, and catch the syntax mistakes that break it.

JSON (JavaScript Object Notation)

A lightweight, text-based data format built from objects ({"key": "value"}), arrays ([1, 2, 3]), strings, numbers, booleans, and null - the standard way most APIs send and receive structured data.

Format vs. Minify

Format ("pretty-print") adds line breaks and indentation so nested data is easy to read. Minify strips all of that out, producing the smallest possible size - what you'd actually send over a network, not what you'd read.

Common syntax errors

Trailing commas after the last item, single quotes instead of double quotes, unquoted object keys, and comments (// or /* */) are all valid in JavaScript object literals but NOT valid JSON - copying an object straight from JS source code is the most common cause of "invalid JSON" here.

Line numbers & error highlighting

Invalid JSON is pinpointed, not just flagged - the exact line named in the error message is highlighted in the editor and marked in the gutter, so you don't have to count lines by hand to find the problem.

Why this stays private

Formatting and validating JSON doesn't need a server at all - your browser already has everything required (JSON.parse/JSON.stringify) built in. What you paste here is never sent anywhere.