Regex Tester & Evaluator
Write, test, and debug your Regular Expressions in real-time. 100% client-side privacy.
Quick Regex Cheat Sheet
[abc] A single character of: a, b or c
[^abc] Any single character except: a, b, or c
[a-z] Any single character in the range a-z
\d Any digit
\w Any word character (a-z, A-Z, 0-9, _)
\s Any whitespace character
a+ One or more of a
a* Zero or more of a
a? Zero or one of a
Free Online Regex Tester & Evaluator
Writing and debugging Regular Expressions (Regex) can be one of the most frustrating tasks for a developer. Our Free Regex Tester provides a real-time, visual environment to test your patterns against sample text. It highlights matches instantly, helping you perfect your code without guessing.
Why Use Our Regular Expression Checker?
- Real-Time Highlighting: As you type your regex pattern or modify your test string, the tool instantly highlights all matches, making debugging incredibly fast and visual.
- 100% Client-Side Privacy: Need to test regex against sensitive log files or user data? Our tool runs entirely in your browser. No data is ever transmitted to remote servers.
- Built-in Error Handling: If your regular expression has a syntax error, our tool will catch it instantly and display a clear error message, saving you from broken code in production.
Common Regex Flags Explained
Flags modify how your regular expression searches for matches. You can toggle these directly in our tool:
- Global (g): Tells the engine not to stop after the first match, but to find all matches in the text.
- Case Insensitive (i): Makes the match ignore uppercase and lowercase differences (e.g., matching both "A" and "a").
- Multiline (m): Changes the behavior of `^` and `$` to match the start and end of each line, rather than just the start and end of the entire string.