Many redirect and callback bugs come from small URL encoding mistakes. A space, ampersand, slash, question mark, or nested URL can change how a query string is interpreted.

A URL encoder decoder is useful when you need to inspect a suspicious value quickly. Decode the URL to understand what it contains, then encode the right parts before using it in a request or redirect.

This is especially common in OAuth flows, payment callbacks, analytics links, search filters, and email campaign URLs. URL encoding is not glamorous, but it is one of those small details that can break an otherwise working integration.