JSON Minifier

The minifier parses your JSON and writes it back with no spaces, tabs or line breaks between tokens. Spaces inside string values are left alone. The built-in sample shrinks from 49 characters to 39:

Because the output is produced from the parsed data rather than by deleting characters, it is always valid JSON. If the input isn't valid, you get an error instead of a half-minified result.

Parsing and re-writing normalises a few things. The data means the same, but the text is different, which matters if you compare files or sign them:

• Numbers take their shortest form: 1.50 becomes 1.5, 1e3 becomes 1000 and 0.1e-6 becomes 1e-7.
• Unicode escapes are turned into the characters themselves, so Caf\u00e9 becomes Café.
• An escaped slash \/ becomes a plain /.

When a key appears twice in one object, only the last value survives. Keys that look like whole numbers are also moved to the front of the object, ahead of the others:

Integers with more than about 16 significant digits lose precision, because they are read as JavaScript numbers. {"id": 12345678901234567890} minifies to {"id":12345678901234567000}. If your payload carries IDs that long, they need to be strings for any JavaScript tool to keep them exact.

The minifier accepts strict JSON only. Three common near-JSON habits stop it with an error:

• Comments, as found in many editor and tool config files. You'll see Invalid JSON: Expected property name or '}' in JSON at position 4 (line 2 column 3).
• A trailing comma after the last item, which gives Invalid JSON: Expected double-quoted property name in JSON at position 8 (line 1 column 9).
• Single quotes around keys or strings.

Remove these by hand and run it again. The line and column in the message point at the first character the parser couldn't accept.