WhatsApp introduces ads in its app

Here’s an advertising model I’ve thought about but never seen:

The app itself is 100% ad free and runs on credits. You get credits through se other portal by logging in to watch ads whenever it’s convenient for you.

Good app experience for the user, and potentially better experiences for the advertisers because they get the target audience when they are most open to ads (and not annoyed by them).

Pretty sure this has been done before but it didn't take off. Personally the hassle of doing this would lead to me just not using the app.

There's no guarantee that the user is "open to ads" in your model. I'd say it's even more likely someone would "watch" the ads while doing something else (AKA not actually watch the ads).

And if you want add something that makes sure the user is paying attention, then you have seen this advertising mode: it's basically the second ever Black Mirror episode.

That's just a paid app with extra steps.

Yeah. It’s a paid app, but it gives people the option of explicitly selling their time/attention via ads if they don’t want to use money.

Most users would probably pay, but some people really don’t want to/can’t and this gives them an option.