Twin — Private Diary App with On-Device AI by BJ Beyond
Twin is a private diary app with on-device AI. You can write or record your day, track mood, sleep and expenses, and ask questions about your own memories. Everything stays encrypted in your browser. There is no account, no cloud journal and no subscription. You pay once and activate with one code.
What you get
- Lifetime access to the Twin web app (version 2.0) with a personal TWIN1 activation code
- The complete 20-page English user guide (PDF)
- Works in modern browsers on iPhone, Android and computer. You can install it to the Home Screen. No App Store needed.
Instant download after purchase: you'll find your files on the order confirmation page and in your email.
Features of this private diary app
Write or record your day
Write text entries or voice notes, then add date, mood, sleep and expenses. You can also set a monthly budget and three personal goals.
Local AI that stays on your device
Optional text AI (Llama/Qwen-class models) and Whisper voice transcription run in your browser after a one-time public model download. Your entries are never sent to an AI server. Local AI can make mistakes.
Patterns, memories and letters
Ask questions about your past entries, look at patterns and scenarios, and write letters to your future self. Answers cite your own notes.
Encrypted by design
Your journal and voice recordings are stored in an AES-256-GCM encrypted vault in your own browser. Encrypted backups use PBKDF2-SHA256 with 600,000 iterations and can be restored at any time.
Device compatibility and AI downloads
| Device or feature |
Requirements and limits |
| iPhone / iPad |
Use an up-to-date Safari and Add to Home Screen. The diary works without AI. Twin selects a lighter local AI mode on iPhone/iPad; full models may exceed the device’s available memory. |
| Android |
Use an up-to-date browser. Local AI uses WebGPU when available, or a slower CPU mode. Support depends on the phone, browser and available memory. |
| Windows / Mac / Linux |
Use an up-to-date browser. A compatible WebGPU GPU enables the GPU model; CPU mode is available and is slower. |
| Voice notes |
Microphone permission is required. Recording and optional local transcription are separate features; transcription downloads an additional speech model. |
Download and storage: the lightweight iPhone AI is about 365 MB; the full CPU model is about 512 MB and the GPU model about 1 GB. These estimates exclude additional runtimes, semantic-memory and speech-model files. Keep at least 1 GB free for lightweight mode and allow more space for other models, recordings and backups. Wi-Fi is recommended.
Before relying on AI: available memory, browser storage and device performance affect model loading. A supported browser does not guarantee that every model will run. Lightweight answers can be simpler, especially outside English. You can keep using the diary without enabling AI.
Offline use and backups: internet is required for the first app load and each model’s initial download. Offline use depends on keeping the downloaded files in the same browser. Clearing browser data can remove your journal and model files; keep an encrypted backup. Public hosting and model servers receive normal download requests, not your diary entries.
How it works
- Buy Twin. Your personal TWIN1 activation code is delivered with your order.
- Open bjbeyond81.github.io/apps/twin/ and paste the code. It is checked offline on your device.
- Create your profile, then save your first memory and an encrypted backup.
Privacy
This private diary app has no account, no tracking of your content, and no cloud copy. The device lock is your access boundary. Keep the code and your backups private. There is no cloud recovery.
FAQ
Is it a subscription?
No. It is a one-time purchase.
Do I need internet?
You need it to load the app and download the optional AI models the first time. After that, the diary and the downloaded AI work offline.
Can I use it on several devices?
Activation is per browser. Each browser or device is a separate local space. To move your journal, use an encrypted backup.
What if I lose my code?
Keep a private copy. You can also show it in Settings → Show activation code. Contact us with your order number if you need help.
Is Twin a medical or therapy tool?
No. Twin is a personal journaling tool. It is not a medical device and does not give medical, psychological or financial advice. In an emergency, call 112.
More about Quiete and this private diary app on the official BJ Beyond page: bjbeyond.it/human-edge-apps.
