01Why I built it

I tried every budgeting app on the App Store. They all wanted my bank login. Not just "view-only read access to your accounts" but the credentials themselves, brokered through a third-party aggregator (usually Plaid) that I'd never signed a contract with and couldn't audit. Some of those aggregators have been breached. The whole pattern made my skin crawl.

The honest truth is most people shouldn't hand their bank password to a budgeting app. It's a normalized practice that probably wouldn't survive 30 minutes of consumer-protection scrutiny if it were happening anywhere else. So I made the version of the app I wanted: zero bank access, ever. You manually enter income; you scan receipts with the camera; the app does the math on a budget that matches your actual pay schedule.

That's PayChunk. It costs $3.99 a year (less than a single Starbucks). No ads. No data sold. No bank account ever touched.

02How it's built (for the curious)

The interesting engineering decisions:

AI receipt scanning. When you snap a photo of a receipt, the image goes to Google's Gemini AI model via Firebase Cloud Functions (keeping the API key off-device). Gemini extracts the merchant, date, total, and line items. The vision model handles crumpled receipts, faded ink, and even handwritten totals. The app caches the result locally so the data never leaves my back end after extraction.

Paycheck-aligned periods. Most budgeting apps assume a monthly cycle. But if you're paid biweekly, the calendar month doesn't match your cash flow — you end up "broke for the last week" every other month. PayChunk instead aligns budget periods to your pay schedule (weekly, biweekly, semi-monthly, monthly), so the math reflects when money actually shows up.

Subscription handling. Server-side validation via App Store Server Notifications V2 — paid status is computed from Apple's signed webhook events, not from the client claiming "I'm a paying user." Prevents the entire class of receipt-spoofing attacks that plagued the early app-store-subscription era.

Built in Flutter, runs on iOS today, Android in closed testing.