The top comment from the last time this was submitted pointed to an open source (AGPLv3) implementation <https://news.ycombinator.com/item?id=29340887> but I don't know how they compare feature-wise
How could one make an app that could host those multiple engines? I've heard that Firefox doesn't embed well, maybe WebKit would be easier? What about Servo or the engine from LadyBird? Is it even possible?
> Responsively App is built on top of Electron and uses Chromium as its rendering engine.
Now I want an app that shows Firefox, Chrome, and Safari side-by-side (besides manually opening them all side-by-side of course).