Query String Parser

The Query String Parser turns the part of a URL after the question mark into a clear list of key and value pairs, and can build a properly encoded query string from fields you provide. Encoding matters because spaces and symbols break a URL if they are left raw, so the tool makes sure each value is safe to send over the wire. Use it when you are constructing a request by hand, debugging why a parameter did not arrive as expected, or standardizing the order of the pairs in a link. It runs locally in your browser. Everything after the question mark in a URL is the query string, a sequence of key and value pairs joined by ampersands that carries parameters to the server. It looks simple and is full of traps. Values containing an ampersand or an equals sign have to be encoded or they will be parsed as structure rather than data, spaces need their own treatment, and repeated keys mean different things to different servers. Reading a query string back as a clear list of pairs is the quickest way to see what a link is actually sending, which is the first step when a parameter does not arrive as expected on the server. The writing direction matters just as much, because assembling a request by hand is where encoding mistakes originate, and a builder that encodes each value guarantees the result is well formed. Ordering is a subtle point that becomes important when a value is used as a cache key or signed, since two links that differ only in parameter order will produce different signatures even though they carry identical data.

📘 Related guide: Break any URL into its parts →