Engine Description Online Testing  
Erlang re module (not available) metadata
Go Package regexp Beta metadata
source
status
uptime
Haskell Text.Regex Beta metadata
source
status
uptime
Java java.util.regex.Pattern Running metadata
source
status
uptime
JavaScript RegExp object Running metadata
source
status
uptime
MySQL String Regular Expression Operators (not available) metadata
source
.Net System.Text.RegularExpressions.Regex Running metadata
source
status
uptime
Perl perlre Beta metadata
source
status
uptime
PHP PCRE Functions Beta metadata
source
status
uptime
Python re module Running metadata
source
status
uptime
Ruby Regexp class Beta metadata
source
status
uptime
Tcl regexp command Beta metadata
source
status
uptime
XRegExp XRegExp object Beta metadata
source
status
uptime

Check out the API specs if you want to add support for another engine

See the different options supported by each engine.