SimpleSave is a self-hostable, privacy-first budgeting API designed for individuals, couples, and households who want full control over their financial data.
The project prioritizes:
- clarity over cleverness
- explicit domain modeling
- incremental complexity
- learnability (Ruby/Rails internals, authentication, domain-driven design)
This repository contains the backend API powering SimpleSave.
- 🏠 Household-first budgeting (solo users included)
- 🔐 Lightweight, explicit authentication
- 🧩 Clear domain boundaries (users vs data ownership)
- 📊 Flexible foundation for budgeting, reporting, and imports
- 🧪 Strong test coverage and predictable behavior
- 🧠 Built as a learning project first, product second
A Household represents a financial space. Every user belongs to at least one household, even when budgeting alone.
Households own:
- categories
- transactions
- budgets (future)
This avoids special cases and makes future sharing trivial.
- Users represent authenticated identities.
- Memberships define which users belong to which households.
- Ownership and permissions are expressed through memberships, not hardcoded roles.
- Categories are scoped to households and archived (never deleted).
- Transactions belong to exactly one household and one category.
- Financial integrity is enforced through explicit constraints.
The following diagram represents the domain model for SimpleSave.
It defines ownership boundaries, authentication primitives, and financial invariants.
- All financial data is owned by households
- Categories are unique per household
- Transactions must reference categories within the same household
- Categories are archived instead of deleted
- Each household must always have at least one owner
Authentication is implemented using:
has_secure_passwordon users- token-based sessions for API access
This keeps the system:
- stateless
- explicit
- easy to reason about
- easy to migrate later to solutions like Devise or JWT if desired
The API uses Minitest with enhanced reporting to ensure:
- clear test output
- fast feedback loops
- confidence in domain behavior
Tests are written to validate behavior, not implementation details.
This project is under active development.
Current focus:
- authentication foundation
- household and membership models
- category and transaction CRUD
- manual transaction imports (v1)
Future iterations will expand into:
- budgeting rules
- reporting and summaries
- import/export flows
- optional bank integrations
This project is licensed under the MIT License.
You are free to use, modify, and self-host SimpleSave for personal or commercial use.
SimpleSave is intentionally opinionated:
- correctness over shortcuts
- explicit over implicit
- boring data models that scale
If something feels simple, it’s because complexity was pushed out of the core — on purpose.