URL Encode and Decode Tool

Use the online tool from above to either encode or decode a string of text. For worldwide interoperability, URIs have to be encoded uniformly. To map the wide range of characters used worldwide into the 60 or so allowed characters in a URI, a two-step process is used:

• Convert the character string into a sequence of bytes using the UTF-8 encoding
• Convert each byte that is not an ASCII letter or digit to %HH, where HH is the hexadecimal value of the byte

For example, the string: François ,would be encoded as: Fran%C3%A7ois

What is URL encoding?

URL encoding stands for encoding certain characters in a URL by replacing them with one or more character triplets that consist of the percent character " % " followed by two hexadecimal digits. The two hexadecimal digits of the triplet(s) represent the numeric value of the replaced character.

The term URL encoding is a bit inexact because the encoding procedure is not limited to URLs (Uniform Resource Locators), but can also be applied to any other URIs (Uniform Resource Identifiers) such as URNs (Uniform Resource Names). Therefore, the term percent-encoding should be preferred.

Which Characters Are Allowed in a URL?

According to RFC 3986, the characters in a URL have to be taken from a defined set of unreserved and reserved ASCII characters. Any other characters are not allowed in a URL.

The unreserved characters can be encoded, but should not be encoded. The unreserved characters are:

The reserved characters have to be encoded only under certain circumstances. The reserved characters are:

Encoding/Decoding a Piece of Text

RFC 3986 does not define according to which character encoding table non-ASCII characters (e.g. the umlauts ä, ö, ü) should be encoded. As URL encoding involves a pair of hexadecimal digits and as a pair of hexadecimal digits is equivalent to 8 bits, it would theoretically be possible to use one of the 8-bit code pages for non-ASCII characters (e.g. ISO-8859-1 for umlauts).

When and why would you use URL encoding?

When sent in an HTTP GET request, application/x-www-form-urlencoded data is included in the query component of the request URI. When sent in an HTTP POST request or via email, the data is placed in the body of the message, and the name of the media type is included in the message's Content-Type header.

External Links

• More information about percent-encoding (Wikipedia)
• URL encoding with Java (UTF-8 character encoding, source code available)

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