RegExr
An interactive workspace for learning, building, and testing JavaScript and PCRE regular expressions.
What it is
RegExr pairs a pattern editor with test text, match details, reference material, and saved examples.
Why it is useful
Results update while you type, which makes small pattern changes easier to inspect than running a script repeatedly.
Who it suits
Developers, data workers, and learners who need to understand a pattern before using it.
Useful for
- Testing a validation pattern against sample input
- Inspecting capture groups and matches
- Learning a regular-expression feature with examples
