: Can punctuation inside a query string be valid? I'm still working on an apache module to fight google's ability to find duplicate content on my website and slashes are apparently throwing apache

@Alves908

Is punctuation perfectly acceptable in the middle of a query string?


Yes, but it depends on the punctuation.

RFC 3986 Section 3.4 defines what characters are permitted in the query string part of the URL:

query = *( pchar / "/" / "?" )
pchar = unreserved / pct-encoded / sub-delims / ":" / "@"
unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~"
pct-encoded = "%" HEXDIG HEXDIG
sub-delims = "!" / "$" / "&" / "'" / "(" / ")" / "*" / "+" / "," / ";" / "="
ALPHA = (letters)
DIGIT = (decimal digits)


Adding all these together gives us the following characters that can be used unencoded:

A-Z, a-z, 0-9, -, ., _, ~, !, $, &, ', (, ), *, +, ,, ;, =, :, @ , /, ?

All other characters must be percent encoded.

However, a few of these characters have special meaning in the query string part of the URL. Notably &, + (encoded space), ; (alt to &) and =. So, if you need to include a literal one of these then it must also be percent encoded.

So, looking at your example:
example.com/?/$=dollar http://example.com/?/=slash example.com/??=questionmark http://example.com/?//=twoslashes


All these URLs are valid as-is (unencoded).

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