Your bank transactions, investment portfolio, and tax returns are about as sensitive as data gets. Nullbook is a new open-source personal finance app that processes all of it locally on your machine, with no cloud storage and no tracking.
What Nullbook Actually Does
The feature set covers a lot of ground for a free tool. Nullbook automatically categorizes transactions, detects recurring subscriptions, estimates federal taxes across different filing statuses, and tracks investment portfolios with gain/loss calculations. It can also scan receipt photos to extract merchant names, amounts, and line items, and it monitors Gmail or IMAP email for purchase confirmations and bills.
For getting data in, it supports CSV, OFX, and QIF imports from banks, plus Plaid integration for automatic account syncing. Self-employed users get Schedule C generation, which alone could save a few hundred dollars in accountant fees during tax season.
Choose Your AI Backend
Nullbook supports three AI providers: Anthropic's Claude, OpenAI, and Ollama. The first two require API keys you provide yourself (meaning you pay per-use directly to the AI provider, not to Nullbook). Ollama is the fully local option, running open-source models on your own hardware with zero data leaving your machine. For anyone paranoid about financial data touching external servers, that's the configuration that matters.
The entire app runs on a local SQLite database. You need Python 3.11+ and Node.js 18+ installed, and there's a single-command installer for macOS and Linux (Windows gets a separate command). It's MIT licensed, so you can fork it, modify it, or run it on your own terms.
Who This Is For
Nullbook sits in an interesting spot. Mint is gone. YNAB costs $99/year. Copilot Money is $70/year. Nullbook is free and gives you more control over your data than any of them. The trade-off is a more technical setup process and no mobile app. For freelancers and small business owners who are comfortable running a Python app and want AI-powered bookkeeping without handing their financial data to yet another startup, it's a compelling option.