Regex Tester
Test regular expressions with match highlighting and capture groups.
Best-fit workflows
Input validation, parser tuning, and log extraction workflows.
How to use this tool effectively
- Open the interactive UI and confirm expected input/output format hints.
- Test patterns against realistic multiline samples including malformed rows.
- Run the transformation or validation, then compare output with an expected fixture.
- Copy, export, or chain the result into the next step of your workflow only after validation.
Practical example
Example: test a log parser regex against mixed timestamps to confirm only valid lines are captured.
Validation checklist
- Check both expected matches and explicit non-matches before shipping.
- Confirm character encoding and whitespace assumptions before concluding output is incorrect.
- Keep sample inputs reproducible so teammates can confirm the same result.
Edge cases to verify
- Greedy groups can consume separators and hide missing fields.
- Regex engines differ in lookbehind and Unicode behavior.
Quality and safety notes
A pattern that passes small samples can still cause catastrophic backtracking at scale.