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🧩 Regex Pattern Builder
Compose regular expressions with guided toggles for character sets, anchors, quantifiers, and flags. Test against sample input instantly.
Regex Pattern Builder
Construct common regular expressions without memorising syntax. Toggle character sets, apply quantifiers, add anchors, and test your pattern against sample input instantly.
Character set
Any characters you add are escaped automatically inside the character class.
0-9a-z_-
Pattern behaviour
/^[0-9a-z_\-]+$/gFlags: g
Test input
jane_doe@example.com
Invoice-1234
HELLO_WORLD
abc123
notes draft
No matches found with the current configuration.
How to use this tool
- Select the character classes you need, then choose an appropriate quantifier.
- Decide whether to anchor the start and end of the pattern.
- Toggle flags (global, case-insensitive, multiline) and test against sample input.
Common presets
- Slug validator: lowercase + digits + hyphen with ^ and $ anchors.
- Invoice codes: uppercase + digits with exact or range quantifiers.
- Whitespace-trimmed tokens: deselect whitespace and include optional symbols.
Remember
- Always escape user-provided input before building dynamic regexes.
- Keep patterns readable by grouping related tokens into character classes.
- Use tests to confirm behaviour across edge cases before deploying.
FAQ
- How do I add start/end boundaries for words?
- Enable the start and end anchors here, then wrap the pattern with word boundary tokens (\b) manually if needed.
- Can I include Unicode character sets?
- Yes. Add them via the custom field, e.g. \u00C0-\u017F for accented Latin characters.
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