What JSON actually requires
JSON (JavaScript Object Notation) is a text format for structured data, standardised as RFC 8259 and ECMA-404. It's the default wire format for REST and GraphQL APIs, config files, and most app-to-app data exchange — small enough to read, strict enough to parse the same way everywhere.
A JSON document is built from six value types: string, number, boolean, null, object, and array. The rules people trip on come from how strict it is compared to a JavaScript object: keys and strings must use double quotes, trailing commas aren't allowed, and there are no comments. When a parse fails, it's almost always one of those — and the error points at the exact character index so you can jump straight to it.
Everything here runs 100% in your browser. The text you paste is parsed and re-serialised locally and never sent anywhere, so config dumps, schema fragments, and anything carrying credentials stay on your machine.
Beautify vs. Minify
Indentation and line breaks that map the structure so a human can read and diff it.
All optional whitespace removed, collapsing the document to a single compact string.
Where developers use it
Reading an API response
Drop a single-line response body in and beautify it to see the nesting and spot the field that came back wrong.
Trimming config for a bundle
Minify local JSON before it ships in client assets to shave a few bytes off the bundle.
Finding the broken bracket
Validate a hand-edited config to locate a stray trailing comma or missing quote by exact position.
Frequently asked questions
No. Formatting, validation, and minification all run in your browser — your data never leaves the page or touches a server. That makes it safe to paste API responses, config files, or anything with keys and tokens in it.
JSON is stricter than a JS object literal. Every key and string must use double quotes ("name", not 'name' or name), trailing commas aren't allowed, and comments, undefined, and functions aren't valid. If your object uses any of those, it'll parse fine in JS but fail here — the error tells you the exact character where it broke.
Beautify adds indentation and line breaks so JSON is easy to read and diff. Minify strips every optional space and newline to shrink the payload for storage or transport. Same data, two representations — pick based on whether a human or a network is the next reader.
Yes — parsing happens locally and comfortably handles multi-megabyte files. The practical ceiling is your device's memory and the browser's string limits, not a server quota.
No, by design. The validator follows the strict JSON.parse behaviour defined by RFC 8259, so it rejects comments and trailing commas instead of silently accepting them. That's what makes it useful for catching the exact issues that break real parsers in production.