Does anyone use have a good regex library that they like to use? Most of the regexes that you find online either contain bugs or are so focused on the edge cases that it turns into a competition to validate whatever spec 100%. Of course you can write your own, but when you are billing by the hour its handy to have a library around.
Besides being pretty much the best Regex tool on the market (seriously), RegexBuddy is about the only tool I know of that lets you switch amongst different Regex rendering engines.
See info here:
RegexBuddy's proprietary regular expression engine allows the software to emulate the rules and limitations of numerous popular regular expression flavors.
Regex is commonly pocket code. What language are you wanting it in? Would you be interesting in contributing to a say google code project that has a standard set of regex's in a few different languages?
Boost, for c++
Lately, I do all my text parsing in Perl. If I needed regex's in another language, I'd go with PCRE.
The PCRE library is a set of functions that implement regular expression pattern matching using the same syntax and semantics as Perl 5. PCRE has its own native API, as well as a set of wrapper functions that correspond to the POSIX regular expression API. The PCRE library is free, even for building commercial software.
PCRE was originally written for the Exim MTA, but is now used by many high-profile open source projects, including Apache, PHP, KDE, Postfix, Analog, and Nmap. PCRE has also found its way into some well known commercial products, like Apple Safari. Some other interesting projects using PCRE include Chicken, Ferite, Onyx, Hypermail, Leafnode, Askemos, and Wenlin.
PCRE is mature, and has the support of numerous projects. Apache and Apple both have a vested interest in making it high-quality. I doubt that any other RE library is likely to surpass it in both functionality and quality (or possibly either) anytime soon.
e-texteditor hilights what you're searching for as you type it. This is incredibly useful, as you can paste your 'sample text' into a file, and just type your regex into the search field, and see what it's matching right in front of you.
None of these 'visual regex builder' things are substitutes for actually LEARNING regular expressions.
This question is too vague. What platform/language are you referring to? Are you also asking for a regex editor/tool as some of the other responses lead?