I've tried every personal finance app. Mint, YNAB, Copilot, spreadsheets, notebooks. They all share the same flaw: they want something from you before they give you anything back. An account. A connected bank. A subscription. A notification permission.
I started building Hollow because I wanted a tool that was completely on my side — no telemetry, no sync, no third party sitting between me and my own numbers. Just a file I open in a browser.
Why a single HTML file?
The single-file constraint is deliberate. When everything — HTML, CSS, JavaScript, even the icon — is embedded in one document, there's nothing to install, nothing to host, and nothing to break. You can save it to your desktop, put it on a USB drive, or open it from a folder. It works anywhere a browser runs.
The best tool is one that's already there when you need it.
There's also something philosophically right about a finance tracker that fits in a single file.
Your data is in localStorage — inside the browser on your machine, nowhere else.
Export it whenever you want. Import it on another device. It's yours.
What I learned building it
The hardest part wasn't the code — it was resisting the temptation to add things. Every feature I cut made the remaining ones more useful. The weekly grid, the budget categories, the savings goals: each one earned its place only by being genuinely useful every week, not just impressive on a product page.
- Constraints produce clarity
- Local-first is underrated — speed and privacy are the same thing
- Good defaults beat flexible configuration
- Dark mode as default is a design statement, not just a preference
Hollow is free to use and always will be. Open it, try it, and if it doesn't fit how you think about money, close it and move on. That's the deal.