SyncFlow – Privacy-Focused SMS/MMS Sync Between Android, Mac, and Web

Name: SyncFlow – Privacy-Focused SMS/MMS Sync Between Android, Mac, and Web
Availability: InStock
Author: solovibecoder

by solovibecoder·Feb 15, 2026·1 point·0 comments

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AI Analysis

●MidSolve My Problem

iMessage alternative for Android users, but execution depends on self-hosting reliability.

Strengths

•E2EE with Signal Protocol + WebRTC video/audio calls provide genuine privacy vs. Google Messages
•Self-hosted architecture keeps message data off big-tech clouds, resonates with privacy audience
•Multi-platform (Android, Mac, web) with real sync infrastructure, not just a wrapper

Weaknesses

•Self-hosting burden—users must run/maintain the backend server, limiting mainstream appeal
•SMS sync to non-Apple devices is crowded: Pushbullet, Join, Telegram; lacks clear technical differentiation beyond privacy angle

Post Description

I built SyncFlow to sync my Android SMS/MMS messages to my Mac and web — without relying on Google Messages or any third-party big tech cloud.

It runs on a dedicated server with a Node.js/Express API + PostgreSQL backend.

The Android app syncs messages, contacts, and call history, and you read/send them from a native Mac app or web client. Your messages never touch Google, Apple, or any third-party cloud.

Key technical decisions: - E2EE with Signal Protocol for message encryption - WebRTC for video/audio calls between devices - MMS attachments stored on Cloudflare R2 via presigned URLs - WebSocket for real-time message delivery + delivery status tracking - Firebase Auth for identity only — message data is fully separate

Stack: Kotlin (Android), Swift (Mac), Next.js (Web), Express + PostgreSQL (Server)

What it does: - Read/send SMS and MMS from Mac or browser - Full contact and call history sync - Video and audio calling via WebRTC - File Transfer between your devices - Spam filtering and scheduled messages

Free tier: 200 messages/month. Paid removes limits.

Downloads: https://sfweb.app/download

Would love feedback on the architecture especially the E2EE implementation and the MMS sync approach.