4Messages is completely ad-free and open source so you don't have to worry about your privacy.

Minimalistic interface, yet intuitive and customizable. You can paint it in any colors. Has four themes: White, Gray, Dark and Black.

Features:
- Dual-SIM and Multi-SIM phones are fully supported
- Backup and Restore your messages
- Support for group chats
- You can block conversations and manage your blacklist, or automatically filter spam using the "Should I reply?"
- Supports Wear OS (Android Wear), TalkBack and Samsung Voice Assistant.

Based on QKSMS.