An Android notification has to do something almost impossible: catch attention without becoming hostile, and stay distinct from every other phone in the room. UX designers spend weeks tuning a single message tone, because the difference between a pleasant chime and an annoying one is roughly two milliseconds of attack. These 63 Android notification sounds were built with that constraint in mind.
You'll find short text notification sounds, custom notification tones for messages, mail and calendar pings, soft music-style ringtones and a handful of voice notifications for accessibility builds. App developers building Android prototypes, indie game devs needing UI cues, and tinkerers replacing the stock pack all use this kind of material. Everything is free to download in MP3, no signup, ready for any Android phone or testing rig.