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HTML URL Encode

Learn how URLs are encoded so they can be safely transmitted across the Web.

When transmitting data over the internet, browsers use a system known as URL encoding. A URL can only be sent using the ASCII character set. Any characters outside this limited set must be systematically converted into a readable format.

The Anatomy of URL Encoding

Since Web URLs rarely consist solely of ASCII characters, special characters (like spaces) must be swapped out for a ”%” symbol immediately followed by two hexadecimal digits representing the character.

For example, a standard blank space is not allowed in a URL link. The browser replaces space characters with %20 or a + sign.

Common Encoded Values

Here is a list of some frequently encountered character replacements in URL structures:

  • Space: %20
  • ! (Exclamation): %21
  • # (Hash): %23
  • $ (Dollar sign): %24
  • & (Ampersand): %26
Preview

Why Can’t I use Spaces?

If a web server receives a raw space character inside a URL path, it might misinterpret it as the absolute end of the request command, leading to a broken 404 Not Found response. Always encode!