URL Encode as its name tells, it is a method to encode special characters in a string. Purpose of this online url encode is to generate encoded urls online. Most of the time it is best tool to share urls to social media profiles and other places where they only accepts url encoded data.
URL encoding actually actually encodes data only when the input data have special characters. These special characters in url will be replaces with a string starting with % and next 2 digit will represent hexadecimal value of byte of that character.