URL Encoder & Decoder Online — Free URL Encode/Decode Tool

URL Encoding: Why and How

A URL can only contain a limited set of ASCII characters. Characters outside this set — spaces, accented letters, symbols like & = ? # — must be percent-encoded: replaced with %XX where XX is the hexadecimal UTF-8 byte value. For example, a space becomes %20, and € becomes %E2%82%AC (three UTF-8 bytes).

🔍 encodeURI vs encodeURIComponent

These are two different functions in JavaScript — choosing the wrong one is a common source of bugs:

Example — encoding a redirect parameter:

🔗 URL Structure

A URL has well-defined components, each with its own encoding rules:

⚠️ Common Pitfalls

• Double-encoding: encoding an already-encoded URL turns %20 into %2520. Always decode before re-encoding.
• Spaces in paths: %20 (correct) vs + (only valid in query strings, form-encoded format).
• Open redirect attacks: if you use a URL query parameter as a redirect target, always validate it's on your own domain — encoding alone doesn't prevent malicious redirects.

All encoding and decoding runs locally in your browser. No data is sent anywhere.