Build, test, and debug regular expressions
In-depth articles on regular expressions — from formal language theory and automata to practical pattern-matching techniques for developers and CS students.
Topics
Step through every node attempt, give-back and capture of a regex match. Zoomable execution flame graph, per-node hot spots, catastrophic-backtracking detection, and verified one-click rewrites. Free, in your browser.
Measure and compare up to 5 regex alternatives under identical conditions — median/P95/P99 latency, throughput, real PCRE2/RE2/.NET engine paths, sub-clock-precision timing and automatic equivalence checking. Free, in your browser.
A new regex flavor for CS theory: test textbook exercises from formal language and automata courses directly in the browser.