Fing is a fast and handy tool for seeing what other devices are on your network.
Official Fing Website
You can download Fing from the Google Play store.
Install
During install it forces you to go through a few options, for the first screen I just clicked “Next”. The second screen has a hidden option under the big blue “Agree and Continue” which says “Review Settings and Policies” and I recommend you click this instead. I turned off “Crash Reporting” and “Allow interest-based ads”. I chose to skim the Privacy Policy which includes “2. Information on MAC addresses and Wi-Fi networks you collect through the App or the Fingbox“. This means I strongly advise you to only allow firewall access to this app on your local internal network/subnet and not allow it full internet access to phone this information home.
You may choose to cancel and uninstall it here until you’re comfortable it can not reach the public internet.
The privacy policy also states under IV(d) “in the event we sell or buy any business or assets, in which case we may disclose your information to the prospective seller or buyer…“
If you then go back and click “Agree and Continue” it’s not obvious if your changes were accepted, and there is no obvious way to go back and check. This is a UX fail.
The next screen says “Enable location” but underneath you can choose “Continue without location”
The next screen says “Sign me in” if you want to create an account, or underneath you can choose “I’ll think about it” which I have done.
The next screen wants to start collecting information about you, but there is a “Maybe later” option at the bottom. You should now be into the application and ready to click:
Scan for Devices
The app will ask you again for location permissions if you denied it during install. I denied it again and it still seemed to work anyway.
The scan happened incredibly fast. It detected the 5-10 devices on my internet network in about 7 seconds with device fingerprinting completed. This means it not only gave the internet address (IP) of each device, but it assigned it an icon depending on the type of device, as well as listing the vendor and model name of each device based on the MAC address.
Summary
This application fails in terms of privacy, it does not keep your scans local to your phone as disclosed in the privacy policy, and they may sell / share your information with pretty much anyone, including your device information and any personal information their scans pick up.
It is effective in terms of offering the intended service, scanning the devices on your network quickly and identifying them.