A private thinking partner and circadian journal powered directly by local Gemma on your phone. Zero remote servers reading your mind. Zero monthly subscriptions. Complete data sovereignty.
The conversations you replay in your head, the messy feelings, the things you'd never post anywhere.
You want to dump your raw thoughts, but you refuse to upload your inner vulnerabilities to cloud LLMs.
You've tried wellness apps with cute mascots, but toxic positivity and gamified streaks felt hollow.
You need a thinking partner that notices your recurring patterns without turning you into training data.
You want clear perspective late at night, without worrying about staff reading your log files for "debugging".
Other AI mental health and journaling apps (Undine, Rosebud, etc.) charge heavy monthly fees to subsidize cloud GPU tokens. Sol runs on your phone.
| Feature / Guarantee | Sol (talktosol.app) | Cloud AI Apps (e.g. Undine) |
|---|---|---|
| Where AI Inference Runs | ✓ Local silicon (NPU / GPU) | × Remote Cloud Servers |
| Who Can Read Your Journal | ✓ Only you (0 bytes leave phone) | × "Staff can access for debugging"* |
| Pricing & Cost | ✓ $0 server token cost | × $20.00 – $69.99 / month |
| Airplane Mode & Offline | ✓ 100% functional offline | × Completely unusable offline |
| Telemetry & Ad Trackers | ✓ Zero Ad IDs & zero tracking | × Analytics & telemetry SDKs |
| Model Architecture | Google Gemma & EmbeddingGemma | Proprietary Cloud API calls |
Three core pillars working synchronously on your device.
Sol shifts its interface and thinking prompts with your biological clock — morning clarity, afternoon grounding, evening decompression, and twilight stillness.
Powered by Google's Gemma models executed locally via LiteRT. Deep emotional resonance, instantaneous replies, and zero cloud latency.
On-device EmbeddingGemma generates local mathematical embeddings of your thoughts. Sol connects the dots across weeks of entries without any cloud sync.
Turn on Airplane Mode. Write your deepest fears, arguments, and reflections. Sol's AI companions and memory run completely unaffected. If an app can't do that, your private life is residing on someone else's computer.
Read the Sol Privacy Manifesto →Sol is currently in Google Play Closed Testing for our initial cohort of testers. Follow these two simple steps to install:
Google Play requires you to be a member of our closed group to gain download access.
Once joined, accept the testing invite on Google Play and install Sol on your Android device.
