A well-documented, easy to modify bulletproof regular expression that matches complete URLs or URL components. Components include:

Schema

• scheme/protocol: use an OR statement to add FTP, etc.
• hostname: use OR statements to more TLDs
• port: matches leading zero; to disable, change the first block in the subexpression to [1-9] from [0-9]
• path
• query: to capture subcomponents of the query string, delete the target symbol in the <?QUERY> subexpression
• fragment

☛ The name of the captured subexpression is usually case-sensitive.

Substitution

Complete URL

${URL}, \1, or its equivalent, can be used to backreference or substitute the complete URL.

• \1
• $1
• ${URL}
• $+{URL}

URL Component Map

${SCHEME}   → \2
${HOSTNAME} → \3
${PORT}     → \4
${PATH}     → \5
${QUERY}    → \6
${FRAGMENT} → \7

Plug & Play substitution/backreference alternatives

• \2\3\4\5\6\7
• $2$3$4$5$6$7
• ${2}${3}${4}${5}${6}${7}
• ${SCHEME}${HOSTNAME}${PORT}${PATH}${QUERY}${FRAGMENT}
• $+{SCHEME}$+{HOSTNAME}$+{PORT}$+{PATH}$+{QUERY}$+{FRAGMENT}