The privacy-first SMS/MMS app that never ships your conversations to the cloud — unless you choose to.
Why QuantaSMS
When carriers push you toward cloud-backed messaging, QuantaSMS is the open-source alternative: modern design, powerful features, and a promise that your SMS stays on your phone.
Grab QuantaSMS-2.0.5.apk from GitHub Releases (~60 MB).
Enable install permission for your browser or file manager.
Android will prompt you — required for any SMS client.
Everything stays on-device. Enable AI or Nearby only if you want.
Our promise
QuantaSMS is not a product you're renting from a cloud company. It's software you own, inspect, and optionally help sustain.
Messages live on your device. Networking is opt-in. No analytics, no ad SDKs, no silent uploads.
GPL v3 licensed. Every line is on GitHub. Fork it, audit it, contribute — no black boxes.
$0 to download. $0 to use. Forever. If QuantaSMS saves you time or peace of mind, you can fuel what comes next.
Capabilities
Carrier-grade messaging with modern compose tooling. Group MMS that actually makes sense, scheduling that respects your life, and dual-SIM support including eSIM labels.
Not just dark mode — a full design system. Pick your vibe or build a custom palette.
Find any conversation, message, or attachment in seconds — with filters that matter.
A private scratchpad inside your messenger — text and voice, never uploaded.
Power-user flows without cluttering the UI. Configure shake, swipe, and double-tap actions.
Bring-your-own intelligence. Cloud API or local Ollama — you choose the model, you trigger every action.
LocalSend-inspired LAN messaging and file transfer. Your Wi‑Fi, your devices, zero internet.
KDE Connect–inspired desktop companion over your LAN — not a cloud relay.
Self-hosted HTTP API for home automation, scripts, and LAN tools.
Grouped rounded cards, section icons, and clear hierarchy — settings that match the app polish.
Deep dive
Google's Magic Compose sends your drafts to Gemini automatically. Quanta AI never touches your messages until you explicitly tap the AI button. Connect GPT-4o with your own API key, or run VibeThinker 3B on a Raspberry Pi — the architecture doesn't care, as long as you control the wire.
Send a photo to your tablet, ping a message to your partner's phone, or share files between devices on the same Wi‑Fi — no account, no upload queue, no corporate server in the middle. Inspired by LocalSend, hardened for Android with PIN pairing, trusted device pins, and stealth mode when you don't want to be discoverable.
Most messengers optimize for engagement. QuantaSMS optimizes for control. Lock the app with biometrics. Block screenshots on sensitive threads. Silence a conversation without deleting it. Export an audit log of every gateway send. Flip local-only mode and the app becomes a island — Nearby, AI, and the developer API all go dark.
Home Assistant alert? Cron job confirmation? Custom CRM ping? The local gateway exposes a simple REST API on your phone's IP. HTTP Basic auth, configurable port, webhook callbacks, and every outbound message recorded in the audit log. It's off by default — and disabled entirely in local-only mode.
POST /message with JSON bodyThe full story
Quantum Messaging · July 2026
On July 6, 2026, Samsung shut down Samsung Messages in the United States and began pushing millions of Galaxy owners toward Google Messages — a closed-source app tied to a Google account, with cloud-routed RCS and Gemini-powered features baked in. For many people that's fine. For the rest of us, it felt like the last local-first option on the default path just vanished.
We built QuantaSMS because we wanted something different: a messenger that looks and feels modern in 2026, but treats your SMS the way SMS was always meant to work — on your phone, under your control, with no silent uploads, no ad SDKs, and no requirement to trust a cloud company with every word you type.
"Your messages aren't the product. You are not the product. The app is free, the code is open, and the network features are opt-in." — The QuantaSMS philosophy
At its core, QuantaSMS is a full-featured SMS/MMS client: inbox, threads, group messaging, scheduled sends, attachments, blocking, archiving, backup export, and dual-SIM support including eSIM labels. But that's table stakes. What matters is everything wrapped around it.
Messages, notes, and settings live on your device. The app works without internet for core SMS. Networking is only for MMS (carrier-required), plus features you explicitly enable.
Quanta AI, Quanta Nearby, Web Companion, and the developer gateway are powerful — and entirely off until you turn them on. Point AI at your own server. Point Nearby at your own LAN.
We didn't slap a black background on a 2014 UI and call it a day. QuantaSMS ships six curated theme presets — Quantum Void for AMOLED purists, Quantum Daylight for bright environments, Quantum Pulse for neon lovers, and more — plus a fully custom theme builder. Settings use a bento-style card layout so you can actually find things. The bottom bar puts Notes, Search, Nearby, and Settings one tap away; compose lives on the FAB where your thumb expects it.
Every major messenger is racing to put cloud AI in your compose bar. We put AI there too — but with a critical difference: you choose the provider, and you choose every invocation. Connect an OpenAI-compatible API with your own key, or run a local model on Ollama. Suggest a reply, rewrite your draft with a tone picker, or summarize a long thread. Your SMS history stays on-device until you deliberately send text to the endpoint you configured.
Remember when you could AirDrop to a friend without creating an account? Quanta Nearby brings that energy to Android: message and file sharing over Wi‑Fi with mDNS discovery, PIN pairing, end-to-end encryption, and stealth mode. No internet required. No corporate relay. Open it from the bottom bar, pair once, and your devices talk directly.
Incognito threads silence notifications and exclude conversations from Web Companion sync. Screenshot blocking stops shoulder surfers. App lock with biometrics keeps the inbox behind your fingerprint. An on-device audit log records every developer-gateway send. Local-only mode is the nuclear option — one toggle disables all networked features. These aren't checkbox features for a privacy policy page. They're tools you can feel.
If you're happy with Google Messages and RCS through Google's servers, QuantaSMS probably isn't for you — and that's okay. We're honest about the trade-off: you won't get cloud RCS chat features. What you will get is SMS/MMS that stays local, an app you can inspect and trust, optional AI and LAN features pointed at infrastructure you control, and a team that builds for privacy-minded Android users — not for ad impressions.
If Samsung's shutdown left you looking for an alternative, if you're skeptical of Gemini reading your drafts, if you run a home lab and want an SMS API on your phone, or if you simply believe messaging apps should respect you — QuantaSMS was built for you.
Download it free. Use it free. If it earns a place on your home screen, consider buying us a coffee. That's the whole business model.
Privacy & security
Hardening tools that most messengers don't even offer — because they're built for engagement, not for you.
Per-conversation privacy toggle. Silence notifications and exclude the thread from Web Companion sync — the chat stays in your inbox, but it won't ping you or appear on your paired desktop.
Prevent screen captures and recordings on sensitive conversations — useful for OTPs, medical info, or anything you don't want saved in a camera roll.
Transparency for power users. Every developer-gateway send and security event is recorded on-device — export, share, or clear when you want.
Biometric or PIN lock for the entire app. Optional end-to-end encryption for SMS between QuantaSMS users who've exchanged keys.
The nuclear option. One toggle disables Nearby, the developer gateway, Quanta AI network calls, and Web Companion — your phone becomes a SMS island.
The entire QuantaSMS codebase is on GitHub under the GNU General Public License v3. No hidden analytics modules. No closed-source "security" blobs in the messaging core. Security researchers, privacy advocates, and curious developers are welcome to read every line, open issues, and submit pull requests.
Community supported
QuantaSMS will never charge for features, show ads, or sell your data. Optional support keeps the lights on for development, device testing, and the roadmap ahead.
No premium tier. No trial. No "upgrade to unlock AI." Download the APK, set it as your default SMS app, and use everything.
Get the APKWe're a small team building for privacy-minded Android users. Donations are optional, transparent, and go toward maintenance, new features, and on-device AI research.
See it in motion
Short ads produced with Volta Studio — your messages on your device, no cloud required.
In the app
A modern Android experience that doesn't look like it was built in 2014.
Honest comparison
We trade cloud RCS for local-first privacy. Here's what you gain.
| Capability | Google Messages | QuantaSMS |
|---|---|---|
| Open source | Proprietary | ✓ GPL v3 |
| No ads / tracking | Analytics & services | ✓ None |
| Works without Google account | ✗ | ✓ |
| Messages local by default | Cloud-backed RCS | ✓ On-device |
| Bring-your-own AI | Gemini (cloud) | ✓ Local or API you choose |
| LAN file & message sharing | ✗ | ✓ Quanta Nearby |
| Incognito / audit log / app lock | ✗ | ✓ |
| Price | Free (data is the product) | ✓ $0 forever · community supported |
Get started
Sideload the APK, set QuantaSMS as your default messenger, and you're done. No account signup. No cloud backup required.
org.quanta.sms.debug so they can sit beside a release install.FAQ
Yes — every feature is free. There is no premium tier, no subscription, and no ads. The project is community supported through optional GitHub Sponsors and Buy Me a Coffee donations.
Yes. QuantaSMS does not require a Google account for core SMS/MMS. Optional features (AI APIs, etc.) are configured by you and only used when you enable them.
Google Messages routes RCS through Google's servers and integrates Gemini in the cloud. QuantaSMS is SMS/MMS-only, local-first, open source, and designed so your messages stay on your phone unless you opt into networked features.
Not currently. QuantaSMS focuses on SMS and MMS with privacy-first local storage. You trade cloud RCS features for keeping conversations off third-party servers.
No. We run no analytics, no telemetry, and no message relay. Quanta AI only sends text to an endpoint you configure, and only when you tap an AI action. Nearby and the developer gateway are local-network only.
Absolutely. The full source is on GitHub under GPL v3. Security researchers and privacy advocates are welcome to read, fork, and contribute.
Download free. Set as default SMS app. No account. No cloud. No catch. Optional donations welcome — never required.