I was paying a monthly subscription for an app that found my recurring charges and tracked my net worth. It did a handful of things well and charged me every month for them. I wanted to know whether I could build the parts I actually used, own the data, and stop paying rent on my own finances.

A full personal-finance app in the shape of Rocket Money. It connects to banks through Plaid, detects recurring payments and subscriptions automatically, tracks net worth across every linked account, and charts income against expenses on daily, weekly, monthly, or yearly views. Subscriptions can be cancelled from inside the app. A built-in AI chat reads your transaction history and answers questions about spending patterns, so you can ask what changed this month rather than scrolling a ledger to find out.

Financial data raises the security bar. Every table runs behind Postgres row-level security in Supabase, so a user's rows are unreachable by anyone else even if a query goes wrong. Bank tokens never touch the client. Balances save to the device first and sync privately to the account, so the app stays usable offline and the network is never the single point of failure for your own numbers.

It replaced the subscription it was modelled on. Every feature I actually used, running on infrastructure I own, on a stack that costs a fraction of what the app it replaced was charging.