Encoding: Transform character string between formats. (Two way) Base64: Is a binary to text encoding that represents binary data in ASCII string format. Used as HTTP parameter in HTTP forms and HTTP GET URLs. Also good to use to encode binary data so that it can be included in URLs, form fields etc.
URL: Converts character string into a sequence of bytes using UTF-8 encoding, so that each letter that is not an ASCII letter or digit is converted to a hexadecimal value of the byte.
Hashing: Maps data of arbritrary size to data of fixed size. Hash functions and values are especially used to verify data by making a thumbprint of the data. If you have the correct/originally data you can calculate the hash value, but not the other way around. (Only one way)
Validation: Validates/Prettify the XML, JSON or CSS presented. If the syntax of XML/JSON is invalid the background will turn red. Prettified output is the result. (Only one way)