The latest YARA-X release now has an official browser playground:

https://virustotal.github.io/yara-x/playground/

You can just run rules in the browser with the WASM build, which is nice when you don’t feel like using the CLI for small tests

LSP runs in a worker, so you get diagnostics/autocomplete and the UI doesn’t hang

Everything is local, nothing gets uploaded. Pretty handy for quick rule testing.