URL-Encoder und -Decoder Online-Tool

URL encoding, also known as percent-encoding, is a mechanism for encoding information in a Uniform Resource Identifier (URI). It's used to convert characters that are not allowed in a URL into a format that can be transmitted over the Internet. This encoding replaces unsafe ASCII characters with a "%" followed by two hexadecimal digits.

• Formatting query strings in URLs
• Sending form data via HTTP requests (application/x-www-form-urlencoded)
• Creating valid URLs with special characters or spaces
• Encoding non-ASCII characters in URLs
• Passing complex parameters in APIs and web services

URL encoding follows these principles:

• Alphanumeric characters (A-Z, a-z, 0-9) remain unchanged
• Special characters like space, ?, &, =, %, + are converted to their percent-encoded equivalents
• Each byte of a UTF-8 encoded character is percent-encoded separately
• A space character can be encoded as "%20" or "+" (in query parameters)
• Reserved characters like /, :, ?, #, [ have special meanings in URLs and may be treated differently depending on their context

JavaScript provides two functions for URL encoding:

• encodeURI: Encodes a complete URI, preserving characters that are part of the URI syntax (like /:?#[]@!$&'()*+,;=)
• encodeURIComponent: Encodes a URI component (like a query parameter value), encoding more characters including those with special meaning in a URI

For most cases when encoding user input or query parameters, encodeURIComponent() is the safer option as it ensures all potentially problematic characters are properly encoded.

Modern browsers encode non-ASCII characters using UTF-8 encoding and then percent-encode each byte. This ensures that international characters, emojis, and other Unicode symbols can be properly included in URLs. For example, the Japanese character "日" is first UTF-8 encoded as three bytes (E6 97 A5) and then percent-encoded as "%E6%97%A5".