Founding Payments Engineer

About Centscape Centscape is a consumer app that helps people save toward the things they actually want — universal wishlists, price tracking, and automatic saving toward their goals. The product is live, and we're now building out the payments and ledger systems beneath it.
The role You'll own the money layer: the systems that move and track user funds from their bank to the balance they see in the app, and the redemption that turns saved balances into the things people are saving for. This is the highest-trust engineering seat on the team. The ledger is the heart of the company's integrity — if it's even slightly wrong, real money ends up in the wrong place — so this role is as much about rigor and judgment as it is about code.
What you'll own

The ledger — the source of truth
Double-entry, append-only, immutable; balances derived from posted entries, not mutable fields
Money in exact minor units (never floats); idempotent postings so retries can't double-count