Regex tester · Guide
How to Test Regex Online
Testing a regular expression online is the safest way to confirm it does what you think. Here is the workflow that turns guesswork into certainty.
Enter the pattern and flags
Type the pattern without the surrounding slashes, then set flags separately. The global flag finds all matches, the case-insensitive flag ignores letter case, and multiline changes how anchors behave across lines.
Paste representative text
Use real input, not a toy example. Include the tricky cases — empty strings, unusual characters, lines that should not match — so the test reflects production data.
Read the matches
Each match shows its value and index. If you get unexpected results, adjust the pattern and re-run until matches line up with intent. Watch for greedy quantifiers that capture more than expected.
Frequently asked questions
Can I use this for production work?
Yes, for inspection, formatting and quick generation. Still review the output before committing it to production code or configuration.
Ready to try it?
Open the free browser-based Regex tester and apply what you just read — no sign-up, runs locally.
Open the Regex tester tool