Ever copied a link and found %20 or %26 in it? That is URL encoding, also called percent-encoding. It keeps links working when they contain characters that have special meaning or are not allowed in a URL.
Why it is needed
URLs can safely contain only a limited set of characters. Characters like spaces, &, ?, #, and non-English letters need to be converted so browsers and servers read them correctly. Each unsafe character becomes a % followed by two hexadecimal digits.
Common examples
| Character | Encoded |
|---|---|
| Space | %20 |
& | %26 |
= | %3D |
? | %3F |
# | %23 |
/ | %2F |
é | %C3%A9 |
A practical example
Say you want to pass the search phrase coffee & tea in a link:
https://example.com/search?q=coffee & tea breaks, because the space and & confuse the browser.
The correct version is:
https://example.com/search?q=coffee%20%26%20tea
In query strings, a space is sometimes written as + instead of %20. Both are common, but %20 is safer in most places.
Reserved vs unreserved characters
- Unreserved (safe): letters, digits,
-,_,., and~ - Reserved (special meaning):
: / ? # [ ] @ ! $ & ' ( ) * + , ; =
Reserved characters only need encoding when you want them treated as data rather than as URL structure.
Encode or decode instantly
Use a URL encoder and decoder to convert text in either direction. If you are creating clean addresses for blog posts or pages, a slug generator will turn a title into a tidy, URL-friendly slug without encoding headaches.
Mistakes to avoid
- Double encoding: encoding an already-encoded string turns
%20into%2520. - Encoding the whole URL: usually you should encode individual parameter values, not the full link including
https://. - Forgetting non-ASCII characters: names with accents or non-Latin scripts must be encoded as UTF-8 bytes.
- Putting secrets in URLs: query strings can appear in logs and browser history. Do not put passwords or tokens in them.
Tips for clean URLs
- Use lowercase letters and hyphens in page paths.
- Keep slugs short and readable.
- Avoid spaces and special characters in file names you plan to link.
