What Is URL Encoding? Percent-Encoding & RFC 3986 Explained

Why Do URLs Require Encoding?

A Uniform Resource Identifier (URI) defined under RFC 3986 can only contain a limited set of ASCII characters. Characters like spaces, quotation marks, ampersands, and non-ASCII Unicode letters can corrupt URL routing or clash with structural delimiters (like ?, &, and /).

Reserved vs. Unreserved Characters

Unreserved Characters (Never Encoded): A-Z, a-z, 0-9, -, _, ., ~
Reserved Characters (Delimiters): :, /, ?, #, [, ], @, !, $, &, ', (, ), *, +, ,, ;, =

The Percent-Encoding Mechanism

Each forbidden character is converted to its UTF-8 byte representation, followed by a percent sign (%) and the two-digit hexadecimal byte value. For example, a space (ASCII 32, hex 20) becomes %20.

Try Related Tools on ToolNest

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URL Encoder

Encode URLs and query string parameters using standard percent-encoding (RFC 3986). Safely encode spaces, ampersands, slashes, and international characters.

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URL Decoder

Decode percent-encoded URL strings and query parameters back into human-readable text. Converts %20, %26, %3F, and UTF-8 hex sequences back into characters.

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URL & Query String Parser

Parse and break down URLs into protocol, hostname, port, path, query parameters, and hash fragments. Inspect and debug URL query string keys and values.

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