URL Encoding Explained: Percent-Encoding, UTF-8, and Special Characters
5 min read
URL encoding (percent-encoding) converts special characters into a format that can be transmitted over the internet. Spaces become %20, ampersands become %26, and non-ASCII characters are encoded as UTF-8 byte sequences.
Why URLs Need Encoding
URLs can only contain a limited set of characters (RFC 3986): letters, digits, and a few special characters (-._~). Everything else must be percent-encoded.
Common Encodings
| Character | Encoded |
|---|---|
| Space | %20 (or + in query strings) |
| & | %26 |
| = | %3D |
| ? | %3F |
| # | %23 |
| / | %2F |
| @ | %40 |
Unicode in URLs
Non-ASCII characters (like café) are first encoded as UTF-8, then each byte is percent-encoded: caf%C3%A9.
In JavaScript
encodeURIComponent("hello world & café")
// "hello%20world%20%26%20caf%C3%A9"
decodeURIComponent("hello%20world")
// "hello world"Generate Clean URLs
Avoid encoding issues by using clean slugs. Our URL slug generator creates encoding-safe slugs automatically.