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Developer Tools
Regex Generator
Turn example strings into accurate regular expressions. Provide positive and negative examples, get a smart regex with explanation, test cases, and flags. Great for beginners and power users alike.
✓ Should Match (2)
user@example.com
test+tag@domain.co.uk
✗ Should NOT Match (3)
not-email
user@
@no.local
Inferred / Editable Pattern
Result: /^[\w.-]+@[\w.-]+\.[a-zA-Z]{2,}$/i
Common email pattern inferred from examples.
Live tester (edit inputs below)
user@example.com✓
bad-input✗
Writing Regex Without the Pain
Regular expressions are powerful but notoriously hard to get right. By showing the generator concrete examples of what should and should not match, you get a pattern that is both correct for your data and reasonably readable. The tool uses smart inference for emails, URLs, phones, dates, IPs and log lines, then falls back to prefix/suffix + length or character class heuristics for everything else.
Tips for Better Results
- Provide 3–6 positive examples that cover the variations you care about.
- Add negative examples that are close but should be rejected.
- Edit the generated pattern directly — the live tester updates instantly.
- Use the editable flags field (i for case-insensitive is commonly useful).