● Developer Utilities
Regex Tester
Test regular expressions with match indices, flags, and capture groups in a Web Worker.
Processed locally. Your input stays in this browser.
Zero Data SentWeb Worker Isolated Execution Active (300ms Hard Timeout)Zero Main-Thread Freeze
//g
Flags:
Matches Found: 0
Worker Execution Time: 0 ms
1 line•69 chars•69 B
Ctrl/Cmd+Enter run
Matched Groups (0)
No matches found for the given expression and test string.
How It Works
- 1.Enter your Regular Expression pattern (without enclosing slashes).
- 2.Toggle flags (g: global, i: ignore case, m: multiline, s: dotAll, u: unicode).
- 3.Paste your test string. Regex runs in an isolated Web Worker with a 300ms termination guard.
Common Use Cases
- •Testing email, phone, or URL validation expressions safely.
- •Debugging search & replace expressions without freezing your browser on pathological patterns.
Frequently Asked Questions
Does this tester safeguard against catastrophic backtracking?
Yes. An isolated Web Worker with a 300ms termination timeout prevents browser freezing.