Originally Posted by felgall
Some browsers have a 255 byte limit and so you should not go over that.
Kind of mate, RFC 2068 says "Servers should be cautious about depending on URI lengths above 255 bytes, because some older client or proxy implementations may not properly support these lengths"
but in reality the best option is not to go above 2000 characters. The 255 limit is set by the RPC, not the browser architecture. Netscape 3+, IE 4+, Firefox (all), Safari (all), Opera (all), Konqueror (all) - all these browsers support up to 2000 characters (and most support more than this). All commonly-used proxy servers, by default, accept long (>255 character) querystrings.
Hope this helps