What is URL Encoding?
URLs can only contain certain "safe" characters from the ASCII character set. Special characters like spaces, ampersands (&), equals signs (=), and non-ASCII characters (like ñ, ü, or Chinese characters) must be encoded as percent-encoded sequences before they can be safely included in a URL.
For example, a space becomes %20 and an ampersand becomes %26.
When Does URL Encoding Matter?
UTM Link Building
Campaign names with spaces must be encoded. "Summer Sale 2025" becomes "Summer%20Sale%202025" — or better, use underscores: "Summer_Sale_2025". Our UTM Builder handles encoding automatically.
API Query Parameters
When building API requests with user-supplied data, all query parameter values must be URL-encoded to prevent injection attacks and malformed requests.
Sharing Links with Special Characters
A search URL like https://google.com/search?q=image compressor needs to be encoded as https://google.com/search?q=image%20compressor to work correctly across all browsers and systems.
Form Submissions
HTML form data is URL-encoded by default when submitted via GET method. Understanding this helps debug why form submissions sometimes arrive with garbled data.
How to Encode/Decode URLs
- Open the URL Encoder/Decoder
- Paste the text or URL you need to encode or decode
- Select Encode or Decode
- Copy the result
Encoding Reference Table
| Character | Encoded |
|---|---|
| Space | %20 or + |
| & (ampersand) | %26 |
| = (equals) | %3D |
| ? (question mark) | %3F |
| # (hash) | %23 |