The short version is that it uses my own engine, called Watson. I used to work for a small game studio inside a big company and my specialty was tooling. I had built my own before I started there and when they shutdown, it evolved into Watson[0].
It's lightweight because it's a static site with no server, it has no spying code or SDKs, and it puts the broadcasters HLS stream URL directly into a <video> element in your browser with minimal intervention.
Maybe a little too well... I tried a whole bunch of channels to get an idea of which ones work, and my history was too full to get out of the site. Maybe every channel change doesn't need to push to your history list.
You know what you need. A button that goes back but instead of going to the prior document goes to the first document with a different domain than the current one.
But speaking only for myself, if history.pushState was removed from my browser I would probably be happier in the end. JavaScript SPA's abuse it 10x more often than they use it appropriately, I'd rather that if you're an SPA anyway, you implement your own in-app navigation and let my browser's mean "get me out of this app". Lord knows SPA's already reinvent every other web standard, why not one more...
Seems to be the fact that there's no advertising, tracking or other SDKs and the entire JS is contained in two files.
But... TV Explorer does keep track of what's tunable (with status lights down the left column) and also lets you scan in the background to find the ones that are live for you right now.
It does only allow filtering by one language at a time, but you can build your hotbar of the stations you like that you find across any filters.
The scan works on the displayed results. If you change the filter, it starts with the new list -- but all the results are saved regardless.
Hope that makes it a bit bitter!
Really great site though!
Quick suggestion: let us resize the channel browser when it's horizontal, and perhaps allow collapsing it altogether
When your window is wide enough (on desktop), you should be able to drag the split point between the TV display and the channel list.