Founding Payments Engineer

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.

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.

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
• Strong transactional and concurrency guarantees no double-spend, no races
• A clear money state machine (pending settled spendable), every entry traceable to its source event

Reconciliation continuous and automated

• Daily tie-out of the ledger against external truth (bank/processor settlement, partner reports, redemption records)
• Break detection and alerting the moment a discrepancy appears
• Tooling and runbooks to investigate and resolve breaks
• A standing invariant: total funds = user balances + in-flight + fees, always

Security of the money layer

• Encryption in transit and at rest; tokenized bank details, no raw credentials stored
• Secrets in a managed vault/KMS with rotation; least-privilege access and segregation of duties
• Full audit logging of every money-affecting action
• Fraud/abuse defense: webhook signature verification, replay protection, rate limiting, anomaly detection
• Secure SDLC and threat-modeling of the flows

The money service

• Orchestrates recurring bank-funded deposits and round-ups under each user's standing authorization
• Handles the hard parts: settlement timing, returns/reversals, retries, dead-letter handling, end-to-end idempotency
• Webhook processing that stays correct under duplicate and out-of-order delivery

Redemption and partner integration

• Integrate payment and redemption partners; reconcile what's issued against what's funded
• Technical lead in partner onboarding

Compliance implementation

• Build the requirements our compliance function defines into the ledger and flows

• Languages: strong in Go (our backend) or an equivalent typed language you can move from; fluent SQL.
• Data: deep with a transactional relational database (Postgres or similar) ledger schema design, isolation levels, locking, and transactional integrity; comfort with event-sourced / append-only designs.
• Async & distributed systems: queues / event streams for webhook and settlement processing; idempotency keys, exactly-once-style processing, sagas, retries, and dead-letter queues.
• APIs & integration: designing and consuming REST and webhook APIs; integrating third-party financial/payment APIs.
• Observability: logging, metrics, tracing, and alerting built specifically around money flows and reconciliation breaks.
• Testing: rigorous testing of money logic property-based tests and simulation of failure modes (reversals, partial failures, duplicate events).
• Practices: secure SDLC, disciplined code review on money paths, and solid CI/CD.

• You've shipped production systems that move real money (payments, banking, lending, payroll, or marketplaces) and owned their correctness end to end.
• You've designed or operated a double-entry ledger and can reason about balance integrity, idempotent posting, and concurrency.
• You've built or owned reconciliation against external financial data, and can walk us through a real break you caught, diagnosed, and fixed.
• Real familiarity with bank / ACH rails and their failure modes returns, reversals, settlement timing.
• Strong instincts for securing financial systems data protection, access control, audit logging, and fraud/abuse defense.
• Fluency in idempotency, webhooks, eventual consistency, and designing for partial failure.
• A correctness-and-security temperament you hold the line on edge cases before shipping, and you mean it.

• Experience with a pay-by-bank / ACH provider.
• Prepaid, gift-card, or stored-value background.
• Exposure to compliance / audit frameworks (SOC 2, PCI) or building toward them.
• Built reconciliation or ledger tooling as a real product surface.

• Founding-level equity plus a salary appropriate to an early-stage company. Happy to discuss specifics early in the process.