get: special chars in url string are not converted, results in 400 bad request about dexador HOT 2 CLOSED

You can also encode with quri:url-encode in Quri (https://github.com/fukamachi/quri) which I believe is already loaded by Dexador and perhaps faster:

(dexador:get (format nil "https://www.last.fm/music/~a" (quri:url-encode "Mötley+Crüe")))

or building the URI with quri:make-uri:

(setq path (format nil "/music/~a" (quri:url-encode "Mötley+Crüe")))

(dexador:get (quri:make-uri :scheme "https" :host "www.last.fm" :path path))

from dexador.

Ok, so here's a solution for user-side conversion of url's special chars.
There is a library, do-urlencode, for coding/decoding of urls.
For the example above, I only need to encode the last url component, otherwise the slashes will also be encoded, among other chars, and dexador doesn't handle that well, it seems.

(ql:quickload :do-urlencode)
(dexador:get (format nil "https://www.last.fm/music/~a" (do-urlencode:urlencode "Mötley+Crüe")))

from dexador.