regexlab-cli

Test, debug, and explain regular expressions from the terminal.

Install

npm install -g regexlab-cli

Commands

Test a regex

regexlab test "^\d{3}-\d{4}$" "123-4567"

Find all matches with groups

regexlab match "\b(\w+)@(\w+\.\w+)\b" "[email protected] [email protected]"
# Or pipe from stdin:
cat emails.txt | regexlab match "\b(\w+)@(\w+\.\w+)\b"

Explain regex in plain English

regexlab explain "(?<=@)\w+\.\w+"

Interactive REPL

regexlab repl

Common patterns library

regexlab patterns           # List all
regexlab patterns email     # Show details for email pattern
regexlab patterns url
regexlab patterns ip
regexlab patterns phone
regexlab patterns date

Available: email, url, ip, ipv6, phone, date, time, hex, uuid, slug, semver, mac, creditcard, jwt, ssn, zipcode, username, password, htmltag, filepath

Generate regex from examples

regexlab gen "2026-03-20" "2025-12-01"

Benchmark regex performance

regexlab bench "\d+" --text "42 lazy dogs"
regexlab bench "pattern" --input large-file.txt

Replace matches

regexlab replace "\d+" "NUM" "I have 3 cats and 5 dogs"

Validate pattern

regexlab validate "(?<=@)\w+"

Features

• Color-coded match highlighting
• Capture group extraction
• Named groups support
• Lookahead/lookbehind explanation
• 20+ built-in common patterns
• Pattern generation from examples
• Performance benchmarking
• Interactive REPL with auto-test
• Stdin piping support
• JavaScript and Python flavor notes

License

MIT