RE
Regex101
The best online regex tester with real-time explanation and debugger.
★ 4.8
Our hands-on rating
✓ Pros
- ✓Real-time regex explanation (token by token)
- ✓Regex debugger with step-by-step execution
- ✓Multiple flavors: PCRE, ECMAScript, Python, Golang
- ✓Free for core features
✗ Cons
- ✗Some advanced features need account
- ✗Server-side processing
Personal hands-on rating (2026-08). The gold standard for regex testing — the explanation panel is unbeatable.
Best for
Developers building or debugging regular expressions.
Not for
Casual users (regex is inherently technical).