Explainer1 min readUpdated June 25, 2026

What is URL encoding (percent-encoding)?

Short answer

URL encoding, also called percent-encoding, replaces characters that are unsafe or reserved in a URL with a percent sign followed by their hex byte value. A space becomes %20 and an ampersand becomes %26, so the URL stays unambiguous.

Why it is needed

Some characters have a special job inside a URL. A ? starts the query, an & separates parameters, and a space cannot appear at all. If a value legitimately contains one of these, it must be encoded so it is read as data, not structure.

search term:  fish & chips
encoded:      ?q=fish%20%26%20chips

Encoding a query value

How it works

Each reserved or unsafe character is replaced with % followed by the two-digit hexadecimal value of its byte. Space is byte 0x20, so it becomes %20; an ampersand is 0x26, so it becomes %26. Non-ASCII characters are first encoded as UTF-8 bytes, then each byte is percent-encoded.

Encode values, not the whole URLEncode individual parameter values, not the entire address. Encoding the ?, &, or / that form the structure would break the URL.

Try it: URL ParserParse a URL to see its query parameters decoded back into readable names and values.Open tool

References

Questions

Why is a space shown as %20 or sometimes +?

In the path and most contexts a space is %20. In the query string of HTML form submissions, a space is often encoded as +. Both decode back to a space.

Is URL encoding the same as Base64?

No. URL encoding only escapes unsafe characters and leaves the rest readable. Base64 re-encodes all the data into a different alphabet. They solve related but different problems.

Does the URL parser upload my link?

No. Parsing and decoding happen locally in your browser tab.