What is URL encoding?

URL encoding (also called percent-encoding) converts special characters into a safe format for URLs. For example, a space becomes %20 (or sometimes + in query strings).

What’s the difference between `%20` and `+`?

%20 is the standard encoding for spaces in URLs. In many web forms and query strings, spaces are encoded as +. If you’re decoding query parameters, keep + as space enabled.

When should I use “Encode all (RFC3986)”?

Some systems prefer stricter encoding where characters like ! ' ( ) * are also encoded. Enable Encode all if you need fully RFC3986-style output.

Why does URL decoding sometimes fail?

A URL can contain malformed percent sequences (like %ZZ) or incomplete escapes (like a trailing %). This tool tries to give a clear error if the input is not valid percent-encoding.