Regex Tester Tool: Test and Debug Regular Expressions Online

Regex Tester Tool: Test and Debug Regular Expressions Online Regular expressions are powerful but unforgiving. A misplaced . or missing escape changes everything. A good regex tester tool lets you see matches in real time, understand what your pattern is doing, and catch mistakes before they reach production. Best Free Regex Tester Tool DevPlaybook Regex Tester — test your regex against multiple strings simultaneously, see matches highlighted, and inspect capture groups. Key features: Live match highlighting as you type Capture group visualization Flag toggles (global, case-insensitive, multiline, dotAll) Reference panel with common patterns No account required How to Test Regex Online Enter your pattern (without / delimiters) Set flags as needed (g for all matches, i for case-insensitive) Paste your test strings See matches highlighted in real time Example: Testing an email pattern Pattern: ^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$ Flags: i (case-insensitive) Test strings: alic