Validation
Check whether user names, emails, or slugs match the intended validation rule.
Pattern testing tool
Regex Tester
Check patterns against sample text, inspect matched groups, and see exactly what your regex is doing before you ship it.
Ready
Guide
How to use a regex tester without guessing.
Regular expressions are powerful because they let you match patterns instead of single literal strings, but that power is also why small mistakes are easy to miss. A tester helps you see whether the engine matched the text you expected, whether your flags are correct, and whether the pattern is too broad or too narrow for the task.
This page runs entirely in the browser, so you can iterate quickly on validation rules, search filters, text cleanup, and scraping rules. When you are done testing, move to the Regex Generator if you need a safer starting point, or compare the resulting text with the Text Diff Checker.
Examples
Common regex testing workflows.
Search
Confirm that your pattern captures the right text before you use it in code or a CMS filter.
Cleanup
Test patterns that remove repeated spaces, tags, or noisy labels from text.
Workflow
What to inspect when a pattern fails.
If the pattern produces no matches, start by checking the flags and the anchors. A pattern that is missing the i flag may fail on case differences, while an overly strict ^ or $ anchor can prevent partial matches from appearing at all. The tester makes those issues visible without opening a code editor.
If the pattern matches too much, reduce its scope by adding literal boundaries, escaping punctuation, or tightening the character classes. Use the preview area to confirm what the engine found in the sample text and copy the final pattern only after the output looks right.
FAQ
Regex Tester questions.
Does the tester support flags?
Yes. You can edit the flags field to test case-insensitive, multiline, or global matching.
Can I see capture groups?
Yes. The output includes the matches and any capture groups from the first match.
Is the matching done locally?
Yes. The regex runs in your browser with no server round-trip.
What if my pattern is invalid?
The page shows the JavaScript regex error so you can fix the syntax before testing again.