Privacy-first data storage options

I'd love to see stronger privacy controls for financial data. This is sensitive stuff - account balances, transaction history, spending patterns - and I think there's a spectrum of approaches worth considering. ## Level 1: Encrypted database storage The simplest step up. Financial data gets encrypted at rest in the database, so even if the DB is compromised, the raw data isn't readable. The server still handles encryption/decryption, so it requires trusting the host. This is table stakes for a finance app honestly. ## Level 2: End-to-end encryption with a user-held key This is where it gets interesting. Each user has an encryption key (derived from a passphrase, or stored in an authenticator/hardware key) that encrypts their financial data client-side before it ever hits the server. The server stores ciphertext it can't read. The tradeoff is that if you lose your key, your data is gone - there's no "forgot password" recovery. Server-side features like search or aggregation become harder too since the server can't see the plaintext, though you could decrypt on the client and do the heavy lifting there. ## Level 3: Fully local / browser-only storage The nuclear option for privacy. All financial data lives in the browser (IndexedDB, OPFS, etc.) and never leaves the device. No server, no trust required. The app works offline by default. The obvious downside is no cross-device sync unless you manually export/import, and if you clear browser data you lose everything. You could pair this with optional encrypted cloud backup that only the user can decrypt - best of both worlds. ## What I think makes sense Realistically, jumping straight to Level 3 is a different product. But Level 2 feels achievable and would be a genuine differentiator - most finance apps ask you to trust them with everything. A "zero-knowledge" mode where the server is just dumb encrypted storage would go a long way. You could even offer it as opt-in alongside the normal mode for users who want convenience over maximum privacy. Worth thinking about how this interacts with features like Monte Carlo simulations and charts - those need access to the raw numbers, so they'd need to run client-side in the encrypted modes. The streaming architecture already pushes data to the client, so maybe it's not a huge leap.