The surprisingly reliable PokeNotify app for tracking wild Pokemon in your vicinity may have been temporarily taken down from the Play Store earlier today, but its alternatives have already started popping up. The first one of them is called "Notifications & More For GO" and is cleverly avoiding the use of the word "Pokemon" in its name as the aforementioned PokeNotify got pulled by Google due to the fact that it was too similar to the actual Pokemon GO app and has consequently violated Google's "impersonation" policy. In any case, just like its impressively original name suggests, Notifications & More For GO was designed to keep you notified of Pokemon in your vicinity while you're running the Pokemon GO app. It even sports Android Wear integration so it's capable of notifying you about nearby Pokemon via your smartwatch and lets you choose your own notification sound.
Unfortunately, setting it up is a bit more complicated in comparison to its alternatives. As the app was specifically designed to work simultaneously with Pokemon GO, it requires a bit more permissions than it can get from an unrooted device. So, if you haven't rooted your latest Android smartphone, you'll have to manually grant the required permission to the app by executing an ADB command from your PC while your phone's connected to it. Don't worry, that sounds much more daunting than it actually is! Just download the Android Debug Bridge tool and enter "adb shell pm grant com.tomer.poke.notifier.android.permission.WRITE_SECURE_SETTINGS" without the quotation marks in the command window while your phone is connected to the PC. Execute that command and you should be good to go.
In case you're paranoid about giving Notifications & More For GO various permissions, do note that the app is completely free and open source so you can see its code for yourself on GitHub. This small but useful piece of mobile software was developed by Tomer Rosenfeld, a 17-year-old Israeli programmer who specializes in Android and web applications development. It's less than 3MB in size and works with any device running Android 4.4 KitKat or newer versions of the OS so you should be able to use it on any device capable of running Pokemon GO.