URL Encoder/Decoder

URL Encoder/Decoder applies percent-encoding to any string so that reserved characters — spaces, ampersands, equals signs, slashes, Unicode — become safe for use inside a URL. Drop in a query string like "q=hello world&lang=zh-CN" and watch each unsafe character get replaced with its %XX equivalent. Decoding reverses the process, turning %20 back into a space and %2F into a slash. This matters in practice far more often than people expect. When you construct a fetch() URL with user-supplied search terms, an unencoded space or & will silently corrupt the request. OAuth redirect URIs, pre-signed S3 links, mailto: links with subject and body parameters, and encoded state parameters in OAuth flows all require correct percent-encoding. If you've ever pasted a URL with a "+" where a space should be, or seen "%20" in a browser address bar, that's this encoding at work. The tool distinguishes between encodeURIComponent (which encodes the entire string including slashes, suitable for a query parameter value) and encodeURI (which preserves slashes and other structural characters, suitable for a full URL). Both directions handle UTF-8 correctly, so Chinese, Arabic, and emoji characters encode and decode without corruption.