Example strings
Each line becomes a sample input for pattern generation.
Email pattern
High confidence/^[^\s@]+@[^\s@]+\.[^\s@]+$/iMatch standard email-style addresses.
Smart Regex Builder
Regex for Password Validation
Generate and test regex for password rules — length, uppercase, digits, and special characters — in a browser-based regex builder that explains the pattern.
- Generate from examples
- Test with live match highlights
- Copy for JS, TS, or Python
Quick modeAutosaves in this browser
Quick templates
Generated pattern
Use the generated regex as-is, or move it into test mode to tweak flags and cases.
/^[^\s@]+@[^\s@]+\.[^\s@]+$/igimsu
Live results
Generate, explain, and validate the pattern in one pass.
See the regex, what it means, and which test lines pass without digging through token noise.
Active regex
/^[^\s@]+@[^\s@]+\.[^\s@]+$/i3 lines • 3 matched • 0 unmatched
Pattern summary
Email pattern • High confidence
Match standard email-style addresses.
const regex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/i;
Match results
One row per test string
Case 1
Matchedalex@example.com✔ Full line matched.
Case 2
Matchedmaya@company.io✔ Full line matched.
Case 3
Matchedtest.user@site.dev✔ Full line matched.
What this regex matches
- Matches the full line from start to end.
- Requires text before and after @.
- Ignores letter case.
- Matches all 3 current test lines.
Show detailed breakdown
^Start of string
Match from the start of the string.
[^\s@]+One or more character outside sets
Match one or more character outside sets.
@@ symbol
Match the @ character.
[^\s@]+One or more character outside sets
Match one or more character outside sets.
\.Literal .
Match the literal character ..
[^\s@]+One or more character outside sets
Match one or more character outside sets.
$End of string
Match up to the end of the string.
Why it helps
Why generate password regex with a builder
Compose length, uppercase, lowercase, digit, and symbol requirements without hand-writing lookaheads.
Test example passwords that should pass and fail so the rule matches your policy exactly.
Read a plain-English explanation of each lookahead so the policy stays reviewable.
How to use it
How to build a password validation regex
1 List the rules your policy needs, like minimum length and required character classes.
2 Test passwords that should pass and near-misses that should fail.
3 Copy the pattern into signup, reset, and change-password validation.
Quick tips
Password regex tips
A common baseline is ^(?=.*[a-z])(?=.*[A-Z])(?=.*\d).{8,}$ — each lookahead adds one requirement without fixing character order.
Length is the strongest single rule; prefer a higher minimum over exotic symbol requirements.
Keep the same regex on client and server so users never see two different verdicts for one password.
FAQ
Password regex questions
Can this generate regex requiring uppercase, digits, and symbols?
Yes. The builder composes lookahead-based patterns for character-class requirements and lets you test them against sample passwords.
How do regex lookaheads enforce password rules?
Each (?=.*X) lookahead asserts that X appears somewhere in the password without consuming characters, so rules combine independently of order.
Should password rules rely on regex alone?
Regex handles composition rules well, but also check length generously and consider a breached-password list — length beats symbol complexity for real strength.
Can I test the password pattern before copying it?
Yes. Test passing and failing examples side by side so the policy behaves exactly as written before it reaches a form.
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