Senior Software Engineer, Ledger

Alt Platform Inc•New York, NY

12d•$200,000 - $220,000•Remote

About The Position

Alt is unlocking the value of alternative assets, starting with the $5 B trading-card market. We let collectors buy, sell, vault, and finance their cards in one place and we are backed by leaders at Stripe, Coinbase, Seven Seven Six, and pro athletes like Tom Brady and Giannis Antetokounmpo. Our next frontier is real-time pricing at scale—the Alt Value that powers every trade, loan, and product on the platform. The Role A collector borrows against a card they own. We size the advance, disburse it, hold the collateral, and manage the loan for however long it runs. Meanwhile an auction closes and hundreds of payouts go out at once, each against a different fee schedule — some by ACH, some by wire, some instant. Every one of those movements has to land in a double-entry ledger that still balances at the end of the day. That is the whole job. You own the ledger that is Alt's system of record, the money movement that feeds it, and the reconciliation that proves the two agree. You are not building a checkout flow. You are building the liquidity that makes this marketplace work. The KPI: 99.99% reliability on gateway and banking integrations, and a ledger where every cent is accounted for and every entry says who created it and when. In payments, "mostly working" is a failure. Financial correctness wants you to measure twice and cut once. The people who are great at this have owned a ledger somewhere it mattered, and they think in idempotency, race conditions, and reconciliation because they've been on the wrong side of all three.

Requirements

5+ years of experience with a heavy focus on backend systems (Python, Postgres, AWS).
Experience with real money movement (ACH origination and returns, RTP or FedNow, wires, or equivalent).
Understanding of NACHA return windows and the impact of credit-push rails on product flow.
Experience with a double-entry ledger (built, migrated, or owned in production).
Experience handling large transactions where failure has significant financial consequences.
Expert SQL and relational design skills.
Ability to write transactions that perform under load, including during peak times.
API-native understanding of webhooks, idempotency, eventual consistency, and reconciliation.
Marketplace or two-sided flow experience.
Obsession with correctness, including deep thinking about idempotency, race conditions, and data consistency.
Product-owner thinking, understanding the flow of funds and clear communication of financial status.
Pragmatism in knowing when to build custom solutions versus leveraging third-party services.

Nice To Haves

React and TypeScript skills sufficient to ship customer-facing surfaces.
Distributed systems experience.
Credit or risk modeling experience.
Direct experience with Stripe, Plaid, Airwallex, PayPal, Modern Treasury, or Increase.
Experience evaluating or implementing a third-party ledger service (Modern Treasury, Fragment, Formance, TigerBeetle or similar).
Stablecoin or on-chain settlement experience.
KYC/KYB, bank partnership, or SOX and audit-readiness exposure.
Experience in the alternative asset space.
Collector of alternative assets or a strong view on the market's future.

Responsibilities

Own the ledger as system of record, including entries, lines, balances, holds, reversals, and their states (pending, posted, available, canceled, declined, reversed).
Design for immutability and audit trail as core constraints.
Provide point-in-time balances for historical customer financial status.
Identify potential schema modeling errors during reviews.
Own Rails and money movement, including ACH origination and returns, RTP and other instant rails, wires, cards, and stablecoin settlement.
Design for different controls for various transaction types (e.g., $300K wire vs. $300 ACH debit).
Own the product consequences of credit-push rails, including auto-charge capabilities and fund finality.
Own Payouts, focusing on speed and options like instant payouts and batch payouts at auction close.
Own Reconciliation, including automated matching, an efficient exception queue, and proactive break detection.
Design and scale lending infrastructure, including credit disbursement, automated loan lifecycle management, repayments, partial payments, advance reversals, and state transitions.
Develop Provider architecture for multi-PSP integrations with a focus on avoiding rewrites and readiness for a single orchestration layer.
Implement webhook handling, idempotency, retry semantics, state machines, and failure modes.
Manage risk on high-value flows, including fraud, dispute, and chargeback posture for high-value transactions.
Set holds, limits, and settlement windows based on data, understanding their impact on conversion.
Implement step-up verification triggered by risk signals.
Make the ledger legible for customer-facing surfaces, including running balance, funding methods, and auction reconciliation.
Make trade-off calls between shipping speed and correctness, and between building custom solutions versus buying third-party services.
Act as a multiplier for the team through rigorous code reviews, technical documentation, and mentorship.