URL Encoder / Decoder (percent-encoding, UTF-8 safe)

What URL encoding is

URLs are restricted to a small set of ASCII characters. To include anything else — spaces, accents, Chinese characters, emoji, special symbols — you replace each unsafe byte with %XX where XX is its hexadecimal byte value. A space becomes %20, a slash %2F, the kanji 漢 becomes %E6%BC%A2 (its UTF-8 bytes percent-encoded).

This calculator uses the browser's built-in encodeURIComponent and decodeURIComponent. It encodes everything that isn't an unreserved character (letters, digits, -._~), which is the right behavior for query parameters and form data.

encodeURI vs encodeURIComponent

JavaScript has two encoders. encodeURI leaves URL structure characters (/ ? & # = + etc.) alone — use it on a full URL. encodeURIComponent escapes all of those — use it on the value inside a query parameter.

This tool uses encodeURIComponent, the safer choice for embedding arbitrary text into a URL. If you have a full URL with structure you want to preserve, encode only the parts that need it.

Common gotchas

Plus sign in URLs. Some servers treat '+' as a space (a legacy from form encoding). encodeURIComponent leaves '+' alone, but a server might decode it to space. To be safe, replace '+' with %2B if you're sending it as data.

Double encoding. Encoding an already-encoded string adds another layer (% becomes %25, so '%20' becomes '%2520'). Always check whether the input is already encoded before running encode again.

Length increase. UTF-8 multi-byte characters expand to 3-4 percent-codes each. A 100-character Japanese string easily becomes a 900+ character URL.