Apps similar to p!n include NotiNotes, which is free and open source. Other options are Notification Notes and Notify me. In total there are three Note-taking Tools like p!n for Android.
A simple notes app, which only lives in your QS and notification panel. Quickly add, view and edit your notes and show them as notifications. All you need to do is adding the tile in your Quick Settings panel and you're ready to note.
Notification Notes is a simple note taking Android app that lets you display your notes as native Android notifications. The notes are displayed as persistent low priority notifications.
Create custom Android notifications within seconds. Create, share, bundle, customize, edit notifications.
