URL Encoding Explained: Why You See %20 in Web Addresses

Oct 20, 2026 · 3 min read · Developer

Ever copied a web address and found it full of strange things like %20 or %3D? That is URL encoding, also called percent encoding. It is how the web handles characters that are not allowed, or that have a special meaning, inside a link.

Why it is needed

A web address can only safely contain a limited set of characters. A space, an accent, an emoji, or symbols like & and = can break the link or change its meaning. So each unsafe character is replaced with a percent sign and two letters or digits. A space becomes %20.

A real example

Imagine a search link with the name "Asha & Ravi". If you put the & in plain, the server thinks a new parameter starts. Encoded, it becomes Asha%20%26%20Ravi and everything works.

encodeURI or encodeURIComponent?

• encodeURIComponent encodes almost everything. Use it for one value, such as a search word.
• encodeURI keeps characters like : / ? & = and #. Use it for a complete address.

Mixing them up is the most common mistake. If you use encodeURI on a single value that contains &, the problem stays.

The plus sign

In form data, a space is often written as +. In a normal address path it is %20. When decoding form data, convert plus to space first. Our tool does that for you.

Decoding errors

If you see "URI malformed", the text contains a % that is not followed by two valid characters. Usually the link was cut off, or someone typed a percent sign by hand.

Tips

• Encode each value separately, then join them with &.
• Do not encode twice, or %20 becomes %2520.
• Test links with unusual characters before sharing.

Try it

Use the URL Encode / Decode tool on our Developer Converters page. Paste your text, pick Encode or Decode, and tick "Whole URL" if you are working with a full link.

Frequently asked questions