Understanding URL Encoding
URL Encoding (also known as Percent Encoding) is a mechanism to encode information in a Uniform Resource Identifier (URI) under certain circumstances. While URIs can technically contain a wide range of characters, many systems (like emails and browsers) only support a limited subset of ASCII characters.
This tool converts unsafe or non-ASCII characters into a format that consists of a percent sign (%) followed by two hexadecimal digits. For example, the space character is encoded as %20.
The Role of Percent Encoding
The primary use case for encoding is to ensure that the URL remains intact when transmitted over the internet. Without encoding, characters like spaces could break the URL structure, or characters like `?` and `&` could be misinterpreted as query delimiters rather than literal text.
Reserved vs. Unreserved Characters
In URL encoding, there is a distinction between characters that must be encoded and those that should not be encoded. This distinction is crucial for keeping URLs readable.
- Unreserved Characters: These characters (A-Z, a-z, 0-9, and `-`, `_`, `.`, `~`) never need to be encoded. They are safe to use in a URL as-is.
- Reserved Characters: Characters like `?`, `/`, `&`, `=`, `+` have special meaning in URLs (delimiters for query parameters, paths, etc.). While you can encode them, the standard is to leave them unencoded unless they are part of the data payload (e.g., a search query containing a question mark).
- Unsafe Characters: Spaces, quotes, angle brackets, braces, pipes, backslashes, and non-ASCII characters (like emojis or accented letters) must always be encoded.
Form Data and Query Strings
When you submit a web form (like a search bar or login), the data is typically sent to the server using the GET method in a "Query String". This string appears after the ? in the URL.
Example
If a user searches for "C++ Tutorial", the browser automatically encodes the `+` sign. The resulting URL looks like this:
https://example.com/search?q=C%2B%2B+Tutorial
If the server receives C%2B%2B, it decodes it back to "C++" to perform the search. This tool mimics that exact process.