RegexTester.dev

A free online regex tester that runs real WASM builds of PCRE2, RE2, .NET, Python, Java, Go, Rust and JavaScript in your browser. Includes a step-through regex debugger with a backtracking flame graph and per-node hot spots, a benchmark suite comparing up to 5 patterns (median/P95/P99, equivalence checking), 9 flavor dialects, an AI regex generator and a 14k+ pattern gallery. Free, no signup, no cookies.