I built a budget app with no backend — everything lives in localStorage
Every budgeting app I tried wanted a monthly subscription. Which is a bit ironic for software whose whole job is to help you spend less. So I built Mochi — and made one architectural decision that shaped everything else: no backend at all. No server. No account. No database. It's a single HTML file, about 75 KB, and all your data lives in your browser's localStorage . Here's what that constraint…
I built a budget app called Mochi without a backend, storing all user data in the browser's localStorage. This unique architectural choice led to several consequences: no synchronization between devices, no recovery option in case of data loss, no analytics for product insights, but also complete security as financial data never leaves the user's browser, and no recurring costs as it's a one-time purchase.
The app is built on a single HTML file, using vanilla JS, and features hand-rolled charts created with plain CSS and SVG. Mochi's standout feature is its dedicated AI-spend ledger, allowing users to log subscriptions, set monthly caps, and monitor six-month trends. The app weighs less than 75 KB and loads instantly, making it faster than most competing budgeting apps.
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