SWI-Prolog -- library(url)

file_name_to_url/2	Translate between a filename and a file:`//` URL.
global_url/3	Translate a possibly relative URL into an absolute one.
http_location/2	Construct or analyze an HTTP location.
is_absolute_url/1	True if URL is an absolute URL.
parse_url/2	Construct or analyse a URL.
parse_url/3	Similar to parse_url/2 for relative URLs.
parse_url_search/2	Construct or analyze an HTTP search specification.
set_url_encoding/2	Query and set the encoding for URLs.
url_iri/2	Convert between a URL, encoding in US-ASCII and an IRI.
www_form_encode/2	En/decode to/from application/x-www-form-encoded.