URL Encoder / Decoder

Why URLs need encoding

URLs only allow a limited set of characters. Everything else — spaces, &, ?, #, non-ASCII text — must be percent-encoded: the character's UTF-8 bytes written as %XX hex pairs. A space becomes %20, & becomes %26, and নমস্কার becomes a run of %E0%A6… bytes. Skip the encoding and your query parameter silently truncates at the first & — one of the classic works-until-it-doesn't bugs.

Component mode vs full-URL mode

The two modes mirror JavaScript's two functions. Component mode (encodeURIComponent) escapes every reserved character — use it for a value you're placing inside a query string. Full-URL mode (encodeURI) leaves URL structure like :/?#&= intact — use it when encoding an entire URL without breaking it. Encoding a full URL with component mode (or vice versa) is the most common URL-encoding mistake; this tool makes the difference explicit.

FAQ

What's the difference between %20 and + for spaces?

Both mean "space", but + is only valid in the query-string part of a URL (a convention from HTML form encoding, application/x-www-form-urlencoded). %20 works everywhere. The decoder here accepts both.

Why does my decoded string throw a "malformed URI" error?

A % in percent-encoded text must be followed by exactly two hex digits. A stray % (say, from "100% free" pasted as-is) breaks decoding — that text was never actually encoded, so there's nothing to decode.

Is my data uploaded anywhere?

No — encoding and decoding run entirely in your browser using the standard JavaScript functions. Nothing is transmitted or logged.