Regex Debugger

Pure frontend: enter a pattern and test text, see matches highlighted live with capture groups. Nothing leaves your browser — ideal for tuning grep -E / sed / patterns in scripts.

Debug a pattern

Pick an ops preset, or type a pattern and test text; matches update live.

Common presets Custom IPv4 address IPv6 address Email URL Unix timestamp Nginx error line Syslog line Regular expression Test text 192.168.1.10 unreachable, 10.0.0.5 tried, gateway 172.16.0.1.

High-frequency ops presets

Preset	Pattern	Use
IPv4	(25[0-5]\|2[0-4]\d\|1\d\d\|[1-9]?\d)(\.(25[0-5]\|2[0-4]\d\|1\d\d\|[1-9]?\d)){3}	Strict valid IPv4
IPv6	([0-9a-fA-F]{0,4}:){2,7}[0-9a-fA-F]{0,4}	Loose IPv6 match
Email	[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}	Match email
Unix timestamp	\b(1[5-9]\d{8}\|[1-9]\d{9})\b	10-digit timestamps
Nginx error line	^\d{4}/\d{2}/\d{2} \d{2}:\d{2}:\d{2}	error.log line start
Syslog line	^[A-Z][a-z]{2} +[ 0-9]{2} [0-9]{2}:[0-9]{2}:[0-9]{2}	syslog line start

Related tutorials

• Linux process & system monitoring — grep usage for log and text extraction