Gabe, the CEO, addresses this directly in the interview. He said that the most lucrative advertising is for things like insurance, cars, etc and that most people just type that directly into the search bar. Advertisers just bid on those keywords and DDG gets paid. They make money from keyword search and advertising.

I think Google used to start with this model too.

Perhaps, but let's not judge DDG on future actions which they may not even take.

Google is beta testing a similar subscription model, but it's only meant to reduce ads so far. https://www.google.com/contributor/welcome/

That's a bit different since it's for a network of third-party web sites, and not Google's own search engine.

It's very different, for a lot of reasons, but the model for revenue is still closer to a subscription model than the normal ad revenue model.

I guess I'm not an average DDG user then :)

Also, at least on their settings page, they encourage donations or the purchase of their gear in order to deal with costs. Nevertheless, I can see how keeping up a free service could be a problem.

I suspect that a lot of people would rather pay directly for a search engine subscription than pay for it indirectly with their privacy. Why hasn't anyone stepped in to serve this market?!

Don't you think their current model can sustain more users? Or do you consider that to be a privacy issue?

I honestly don't know enough to judge the financial sustainability of the company. To me it's more about incentives.

Right now it seems they're still growing really fast. What if tomorrow it's not the case anymore? What if their userbase reaches a plateau? Will they really still be morally strong enough to commit to user privacy or will they slowly start to give in more and more in order to increase their revenue? Does "do no evil" ring a bell?

On the other hand if they get money from the users themselves then the incentives are different, they might try to get more money by offering new services and they probably won't risk doing that that'll piss off their paying users.

Maybe I'm too cynical but in my mind even if ddg's intentions are pure now eventually they'll get bought or something and someone, some day will want to cash in. And for a free service cashing in means selling the userbase to the highest bidder.

But maybe I'm a bit naive, I guess that would still be possible even with paying users but I think the risk would be greater for them.

What data do you think DDG has on you now, that they could sell? Or is your concern that DDG could cell out on the promise of users, and that users would fail to notice a change in privacy-respecting behavior?

Precisely, yes. As with all internet services we can't really audit what's being collected as simple users, we have to trust them to "do no evil". If tomorrow ddg started logging my browsing history in order to better target ads for instance I probably wouldn't notice a thing.

This depends on the stack. If the cost grows faster than your revenue than it is a problem. If they have a lean stack where the cost grows slower than the revenue by the number of users they are good.