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Convert delimited text and JSON both ways.

Escape and unescape HTML and XML entities safely.

Decode a JWT header and payload, client-side only.

Test any number for primality with Miller-Rabin, then get its prime factorisation and every divisor.

Mean, median, mode, quartiles, range and standard deviation for any list of numbers.

Add tax to a net amount or strip it back out of a gross amount, with common rates one click away.

Layer up to three shadows with x, y, blur, spread, opacity and inset, then copy the CSS.