Senior Software Engineer, Payments

Alt Platform Inc • New York, NY

1d • $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
An auction closes and every seller in it gets paid in the same moment, each against a different fee schedule — some by ACH, some by wire, some instant. A buyer funds a five-figure purchase and the bank returns it three days later. A webhook arrives twice, out of order, from a provider that was down for an hour. Every one of those movements has to reach the right account, on the right rail, at the right time, and land in the ledger exactly once.
That is the whole job. You own how money physically moves at Alt: the providers, the rails, the orchestration layer that routes between them, and the risk posture that keeps a marketplace of high-value transactions safe. The ledger team owns the record; you own everything that happens between a customer's bank and that record. 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 time-to-funds for sellers and borrowers that we measure, publish, and beat every quarter. In payments, "mostly working" is a failure.
The people who are great at this have integrated a provider that lied to them, and they design for the third retry, the late return, and the duplicate callback 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.
• You've worked on real money movement. ACH origination and returns, RTP or FedNow, wires, or equivalent. You know what an R01 is, why NACHA return windows matter, and why a credit-push rail changes the product flow and not just the API call.
• You've integrated more than one payment provider in production, and you've lived through one of them failing.
• You've handled large transactions, where the failure mode is a five- or six-figure problem and someone notices immediately.
• You're API-native. Webhooks, idempotency, eventual consistency, and exactly-once delivery are your default vocabulary.
• Strong SQL and relational design. You know how to write a transaction that won't fail under load — including at auction close and during scheduled auto-pay batches.
• Marketplace or two-sided flow experience. Buyers and sellers, settlement between them, and the timing tension that creates.
• An obsession with reliability. You think deeply about idempotency, race conditions, and what happens on the third retry.
• Product-owner thinking. You don't just build a pay button. You understand the flow of funds and how to communicate financial status clearly to a user who is worried about their money.
• Pragmatism. You know when to build a custom internal solution and when to leverage a third party to get the job done.

Nice To Haves

• Direct experience with Stripe, Plaid, Airwallex, PayPal, Modern Treasury, or Increase, and with evaluating or building a payment orchestration layer across more than one of them.
• Fraud, dispute, or chargeback work on a marketplace; hands-on with risk tooling like Sardine, Sift, or Stripe Radar; enough React and TypeScript to ship the payment-method and payout surfaces you own.
• Distributed systems; stablecoin or on-chain settlement; KYC/KYB, bank partnership, or bank-sponsor program exposure; the alternative asset space. You collect, or you have a view on where this market is going.

Responsibilities

• Rails and money movement. ACH origination and returns, RTP and other instant rails, wires, cards, and stablecoin settlement. A $300K wire and a $300 ACH debit are different products with different controls, and you'll design for both. Credit-push rails change what you can auto-charge and when funds are final — you'll own those product consequences, not just the integration.
• Provider architecture and orchestration. Multi-PSP integrations built so the next one isn't a rewrite, and a single orchestration layer that routes each movement to the right provider by cost, speed, and health. Webhooks, idempotency, retry semantics, state machines, failure modes on the third retry, and provider failover that nobody notices.
• Payouts and collections. Getting sellers and borrowers their money faster than anyone else in this market: instant payout options, batch payouts at auction close, and the rail and timing choices that make them safe. On the other side, cash advance disbursement and the scheduled auto-pay batches that collect repayments run on your rails. The ledger team decides what a pending balance means; you decide how and when the money actually moves.
• Risk on high-value flows. The fraud, dispute, and chargeback posture for a marketplace where one bad transaction is a five- or six-figure problem. Holds, limits, and settlement windows set with data — and you'll know what each one costs in conversion. Step-up verification triggered by risk signals rather than blanket friction.
• Payment operations. When a transfer is stuck, a return code is unfamiliar, or a provider goes quiet mid-batch, you find out why. You'll own the tooling that lets operations and support answer "where is my money" without paging an engineer, and you'll feed clean, complete processor data to the ledger team's reconciliation so their breaks are real breaks and not missing webhooks.
• The posting contract, from the producer side. Every movement you originate lands in the ledger through a typed contract the ledger team owns. You'll build against it, push on it when a new rail doesn't fit, and guarantee exactly-once delivery into it.
• The trade-off calls. Shipping speed against uncompromising reliability; build custom versus buy an orchestration platform. You'll be asked to defend both directions.
• The team. Be a multiplier through rigorous code reviews, technical documentation, and mentorship.

Benefits

• We cover 85% of your medical, dental, and vision, and up to 50% for dependents. HSA/FSA available
• Generous PTO that people actually take
• Parental leave at full salary
• $200/month wellness + $100/month home office stipend
• Free DoorDash Pass membership, because dinner shouldn't be a decision
• Remote-first (for most positions), with WeWork access when you want a room with other humans
• 401(k)
• Alt Equity to all full-time employees

What This Job Offers

• Job Type: Full-time
• Career Level: Senior
• Education Level: No Education Listed