Sexy examples

Innermost HTML tables

SSN

^(?!000|666)(?:[0-6]\d{2}|7(?:[0-6]\d|7[012]))-(?!00)\d{2}-(?!0000)\d{4}$

ZIP codes

\b[0-9]{5}(?:-[0-9]{4})?\b

Regex with errors

Following are a few examples of the kinds of syntax errors and cross-browser headaches that are detected and flagged in red:

Hello+?? x*+ |? a{1,2}b{2,1} |(?:a|b)* (?=x)* (?<=n) (((((((a)))b.c)d|x(y){65535,}z{65536,}))))
[1-59-6\b-\cX.a-\w!---] \xFF \x \uFF\uFFFF\z\v\\\