It seems like a promo link which gives you 500mb per month for free. You have to pay for unlimited data.

From the number of YouTube channels that promote them, I expect they must have a strong affiliate program. Just a possible bias to keep in mind...

Its a nice user-friendly app, works well on all my stuff. Using it on linux took a bit of manual setup, but their instructions worked. I'm a customer, and I would recommend it. I outsourced my trust in them to DDG. Hopefully they didn't steer me wrong there.

Downside is that it basically only works per device. It doesn't run on any routers that I know, to get full coverage over your network traffic.

User-friendly, but blocks port 22, so if you need SSH and can't change the port, try something else.