URL Encoding

URLs can only contain a limited set of characters as defined in RFC 3986. Special characters or non-ASCII characters (e.g., German umlauts) must be encoded to avoid conflicts or misinterpretation.

What is URL Encoding?

URL encoding is a method to convert special characters in a URL into a safe format. This is essential because URLs are restricted to specific characters, such as letters (A-Z, a-z), numbers (0-9), and a few symbols (-, _, .).

Characters that do not meet this rule, such as spaces, #, or non-English letters (ä, ë, à), must be encoded. Other characters (e.g., /, ?, &) have specific meanings in URLs and can only be used as encoded values in query parameters.

Encoding replaces each character with a combination of:

1. A percent sign (%).
2. Two hexadecimal digits, representing the ASCII or UTF-8 value of the character.

For the OpenPLZ API, this primarily concerns the values and regular expressions used in the URL parameters searchTerm, name, postalCode, and locality.

Which Characters Must Be Encoded?

1. Special Characters and Spaces:

   • A space becomes %20.
   • & becomes %26.
   • = becomes %3D.
   • etc.

2. Non-English Letters (Umlauts, Accents, etc.):

   • ä becomes %C3%A4.
   • ö becomes %C3%B6.
   • à becomes %C3%A0.
   • ë becomes %C3%AB.
   • etc.

3. Other Special Symbols:

   • # becomes %23.
   • + becomes %2B.
   • / becomes %2F.
   • etc.

Example

The following OpenPLZ API example returns all streets in München where the postal code starts with 808:

• Original:

  GET https://openplzapi.org/de/Streets?postalcode=^808&locality=München
  

• With URL encoding:

  GET https://openplzapi.org/de/Streets?postalcode=%5E808&locality=M%C3%BCnchen
  

  Here, the circumflex ^ in the regular expression is encoded as %5E, and the umlaut ü in "München" is encoded as %C3%BC.

Tool

The following tool helps you to encode any value. To do this, type the text into the first text field and click on ‘Encode’.

Encode

You can see the URL encoded result here:

Encoding Tables

Latin Characters with Accents and Diacritics

Special Characters