It would take me some effort to make and maintain a separate version. Users would report bugs which have been fixed months ago, because they did not update it, etc.

I think the importance of "offline apps" is overrated today. Personally, I spend less than 10 hours a year on a device without internet, and I think this number is decreasing each year, for everyone.

People use Google Maps and Wikipedia without having them on their hard drives. On the other hand, it is nice, that you can simply close a website and there is no track of that service in your computer.

Maybe a Progressive Web App could work? If I remember correctly, it requires basically just adding a cache manifest.

Initial setup can be finnicky (test it on a separate subdomain!) but it shouldn't require much more than a correctly configured cache manifest and a few lines of code to handle updates.

there are even some frameworks that make it extra easy, like angular for example (just `ng add @angular/pwa` and you're basically done).

while it is pretty easy and doable in maybe 1-2 days, depending on how fluent you are with these kinds of things... it's not entirely in the authors best interest. if people start using it `offline`, he wont be able to get advertisement revenue after all ;)

He says in one of his Reddit comments that he does not (and probably will not) use frameworks. It's pure HTML/CSS/JS.

Careful! You can get users stuck on an old version if you configure it incorrectly

Doesn't deleting the manifest solve that? I thought serving a 404 for it makes browsers delete their cache exactly to provide a way out of this trap.

But yes, this is why I suggested testing with a separate subdomain.

Why bother. He already has very nice product and makes very nice money.