How We Do Bank-Grade Encryption and Cross-Device Sync Without Running a Server
Most budgeting apps store your financial data on their servers. This means: They can see your transactions, balances, and spending habits A server breach exposes your financial life If the company shuts down, your data may be lost They can — and often do — monetize aggregate financial data We built Zeroed to make all of these impossible. Here's the architecture. Local-first architecture Zeroed…
Budgeting apps typically keep users' financial information on their servers, which means the apps can access sensitive data such as transactions, balances, and spending habits. If a server is breached, users' financial lives could be exposed, and if the company shuts down, users' data might be lost. Additionally, these companies can monetize aggregate financial data. To address these concerns, Zeroed was created to eliminate these issues through its architecture.
Zeroed employs a local-first approach, storing the entire financial database on the user's device within an encrypted SQLite database. The encryption key is derived from the device, and it's never transmitted anywhere, so the company cannot read, lose, or sell users' data. Instead of using a server, Zeroed utilizes Google Drive for cross-device synchronization.
When users enable sync, Zeroed creates a folder called ZeroedData in their personal Google Drive using the drive.file scope, which restricts access to only the files it created. The encrypted database is then uploaded to this folder, and any other device with the Zeroed app and the same Google account will automatically detect the folder, download the encrypted database, and decrypt it locally.
Licensing in Zeroed is also serverless. The license key is stored in the user's ZeroedData folder, so any device signed into the same Google account will see the key and unlock the full app without needing a license server. This means there are no activation limits or errors indicating that the user has used too many devices. All data synced through Google Drive is encrypted with AES-256, the same standard used by governments and financial institutions.
Encryption happens on the user's device before data is sent to Google Drive, and decryption occurs on the device after download, ensuring that unencrypted financial data never exists outside the device's memory.
The benefits for users are clear: they can switch phones freely, sign into Google Drive to sync across devices, and use the app fully offline when not connected. Their financial data remains mathematically inaccessible to anyone but themselves. The author of Zeroed is available to answer questions about the architecture, including trade-offs like conflict resolution, key management, and the no-web-app constraint.
Zeroed is a pay-once, offline envelope-budgeting app for Windows and Android, available with a 34-day free trial without requiring a card.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
