[ameshkov]

You may have looked on a bad one.

System-wide blockers on both iOS and Android do use the VPN API, but the idea is to intercept your outgoing traffic on the TUN interface, emulate the TCP/IP stack, and filter it locally, right on your device.

[49bc]

How do you know which one the app is doing? From my perspective the vpn was “on”

[ameshkov]

The easiest way would be to visit a website like "whatsmyip" and check that your IP address stays the same.

[hedora]

Not perfect, but you could connect to wifi, and look at the connections the phone makes.

Of course, it could change its behavior if it detects a cellular connection...

[saagarjha]

A better way would be to download the app and reverse engineer the binary.

[49bc]

And do that every single time there’s an update?

[gruez]

or download an open source version on f-droid

[sofaofthedamned]

Exactly. It's a VPN in name only, and the only reason is to route traffic to be able to bypass the security features in the OS.