Regex Lab
Build, test, and debug regular expressions with real-time match highlighting, capture group inspections, and bounded execution timeouts to prevent browser freezing.
Presets:
//
Test String
Match Results
2 matches
0.2ms
Contact us at support@codecrest.dev or engineering.team@company.co.uk. Invalid: test@.com
Match Breakdown
| # | Match | Range | Capture Groups |
|---|---|---|---|
| 1 | support@codecrest.dev | 14–35 | — |
| 2 | engineering.team@company.co.uk | 39–69 | — |
Common Regular Expression Flags
g (global)
Finds all matches rather than stopping after the first match.
i (ignoreCase)
Matches letters without distinguishing between uppercase and lowercase.
m (multiline)
Treats beginning and end characters (^ and $) as working across each line.
s (dotAll)
Allows the dot special character (.) to match newline characters.
u (unicode)
Enables full Unicode pattern matching and emoji handling.
ReDoS Guard
Executes expressions with bound execution windows. If an exponential backtracking pattern triggers, execution halts gracefully.
Real-Time Evaluation
Calculates matches dynamically as you type, rendering color-coded marks and range coordinates.
Production Presets
Includes validated patterns for emails, IPv4 addresses, URLs, SemVer numbers, and ISO 8601 dates.