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This site allows you to do a regex test, i.e. it utilizes JavaScript (AJAX) to instantly validate regular expressions (regex), by searching and replacing strings in a text based on the regular expression. The result is live, it is updated instantly while you type, without any submission of forms and extra clicking, thus allowing fast and easy edit of regular expressions, having a constant clue what they exactly do. This tool is constantly improved to stay the most advanced since it has been the first to utilize AJAX technology for testing Perl (PCRE) and PHP (POSIX) regular expressions. Currently this site is able to test JavaScript, PCRE and POSIX dialects. JavaScript dialect is used in ECMAScript, JScript and VBScript programming languages. PCRE dialect is mainly used in Perl, PHP, Apache's .htaccess, grep and most software. POSIX is mainly used in PHP and UNIX programming languages. Despite there may be some differences in most cases all regular expressions regardless the dialect are compatible.