Sylex
Make sense of the slashes.
What it is
Sylex is an interactive regex explainer that breaks any pattern down into its parts and tells you what each one does. It runs on a hand-rolled lexer rather than the browser's regex engine, which is what lets it flag ReDoS-prone constructs and power a native $-expansion replace mode in the same pass. It is a from-scratch, dependency-free build that runs entirely in the browser, so you can download it and run it locally.
A hand-rolled regex lexer powers the explainer; ReDoS detection and native $-expansion replace mode round it out - all client-side, dependency-free.
What's inside
The full source, the tests, and CI. Open it, read it, change it. A zero-dependency core, free, in the MIT spirit.
Run it after unzip
pnpm install && pnpm dev