TextNow - TextNow is a mobile virtual network operator (MVNO) that provides a free phone service to users by using other cellular networks coverage.

Textnow.com - It lets you text your friends, aka my only source of happiness

TextMe - TextMe is a free calls and messaging application at both local and international levels.

aTalk - An encrypted instant messaging with video call and GPS features for android.

Talkatone - Android App on. Google Play. Stop paying for cell minutes, texts & landlines; Turn your iPad or iPod touch into a phone; Call/Text even in areas with bad cell coverage; Call/Text when travelling without paying for expensive international minutes.

Molly (Signal fork) - Molly is an independent Signal fork for Android