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Encode and decode URLs and query strings. Convert special characters for safe URL transmission.
URL encoding (percent-encoding) converts special characters into a format safe for transmission in URLs. Characters like spaces, ampersands, and question marks are replaced with a percent sign followed by two hex digits (e.g., space → %20).
0 characters
| Char | Encoded | Usage |
|---|---|---|
| Space | %20 | Most common encoding |
| ! | %21 | Exclamation mark |
| # | %23 | Hash/pound (fragment) |
| $ | %24 | Dollar sign |
| & | %26 | Ampersand (query separator) |
| ' | %27 | Single quote |
| ( | %28 | Open parenthesis |
| ) | %29 | Close parenthesis |
| + | %2B | Plus sign |
| , | %2C | Comma |
| / | %2F | Forward slash (path) |
| : | %3A | Colon (protocol) |
| = | %3D | Equals (query value) |
| ? | %3F | Question mark (query start) |
| @ | %40 | At sign |
Encoding: Converts unsafe characters to percent-encoded format using encodeURIComponent(). This encodes all characters except A-Z, a-z, 0-9, and - _ . ! ~ * ' ( ).
Decoding: Converts percent-encoded sequences back to their original characters using decodeURIComponent().
100% Client-Side: All processing happens in your browser. Your data never leaves your device.
Formula
encoded = '%' + hex(byte1) + hex(byte2) per UTF-8 byte% = Percent sign prefix for each encoded byte sequence
hex(byte) = Two uppercase hexadecimal digits representing the byte value
UTF-8 byte = Non-ASCII characters may require 2–4 bytes each
Worked Example
Encoding "café"
Did you know? Percent-encoding (URL encoding) was first defined in RFC 1738 in 1994. The modern standard, RFC 3986, reserves 18 characters with special URL meaning — all others must be percent-encoded when used as data values.
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