Free Regex Tester Helper calculator with clear step-by-step results.
Compiles a regular expression with the flags you select and reports how many times it matches the sample text, what the first match is, and how many capture groups the pattern defines. Invalid patterns are caught and reported rather than throwing.
Flag construction
Flags = i when case insensitive, g when finding all matches
Group count
Capture groups are counted from the length of a match array against an always-matching variant of the pattern
Without the global flag, matching stops at the first hit. With it, the engine continues scanning, which is why the count jumps from one to many on the same pattern.
No. Only numbered and named capture groups are counted; (?:...) groups affect precedence but capture nothing.