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dmyersturnbull/normalized-dns-uri.regex

Last active February 13, 2026 01:09
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Regex for canonical public-facing URIs. Specifically, matches lowercase, ASCII (or Punycode-encoded) RFC 3986 URIs with DNS hostnames and no credentials. Per spec, allows empty path segments; unencoded `:`, `@`, `/`, and `?` selectively; and unencoded sub-delimiters. Dialect is ECMA-262 2025 with whitespace.
Raw
normalized-dns-uri.regex
^
(?= .{1,255}+ (?:$|/) )
(?! \d{1,3}(?:\.\d{1,3}){3} ($|/) )
(?<host>
[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?
(?: \. [a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])? )+
)
(?<path>
/ [-\w.~!$'()*+:@;,&=]*
)?
(?<query>
\? [-\w.~!$'()*+:@;,&=?]*
)?
(?<fragment>
# [-\w.~!$'()*+:@;,&=?]*
)?
$
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