This is the browser repl-env https://github.com/clojure/clojurescript/blob/r1.10.773-2-g946348da/src/main/clojure/cljs/repl/browser.clj This is the figwheel repl-env https://github.com/bhauman/figwheel-repl/blob/master/src/figwheel/repl.cljc#L1374 They both implement the same abstraction, but they are very different implementations. The Figwheel one is more advanced and supposed to solve some problems with the regular browser repl-env, but it's also finicky to get working outside of figwheel. I don't recommend you use it unless you're going to dive in and debug things at a low level. When using the browser repl-env you generally let it open the browser / tab for you. I don't know what your options are if you want to launch it yourself. It will not reconnect to a tab/window that's open from a previous run. This is all sub-optimal, which is why we created kaocha-cljs2 and funnel, where you have much more control over where your tests run, you can start the browser yourself, it will reconnect, etc.

ah I see, should I try to kaocha-cljs2 instead?

and well I'm having some issues with one project, but there is another similar project that works just fine, so I guess it's just something I'm doing wrong

I thought from the docs that I had to start the browser myself on Linux