Staff Software Engineer, Ledger

Alt is a company unlocking the value of alternative assets through a platform for buying, selling, vaulting, and financing trading cards. The Staff Software Engineer, Ledger will independently build and own the ledger, payment rails, reconciliation, payouts, lending infrastructure, and risk controls, with a strong focus on financial correctness and AI-enabled tooling.

Responsibilities:

• The ledger as system of record. Entries, lines, balances, holds, reversals, and the states between: pending, posted, available, canceled, declined, reversed. Immutability and audit trail as design constraints, not features. Point-in-time balances that show a customer where they stood on any past date. Done looks like an auditor pulling a trial balance without asking you for help
• Rails and money movement. ACH origination and returns, RTP and other instant rails, wires, cards, and stablecoin settlement. A credit-push rail changes what you can auto-charge and when funds are final, and you own those product consequences, not just the integration. Done looks like the fourth PSP costing a sprint, not a rewrite
• Reconciliation. When the ledger and the processor disagree, you own the answer. Automated matching, an exception queue a human can actually work, and breaks caught before a customer finds them. Every point of automation here is a point on the north star
• Payouts and lending infrastructure. Getting sellers and borrowers their money faster than anyone else in this market: instant payout options, batch payouts at auction close, and the settlement timing that makes them safe. Then the full loan lifecycle, disbursement through repayment, partial payment, delinquency, and collateral release
• Risk posture on high-value flows. Holds, limits, and settlement windows set with data, and you will know what each one costs in conversion. Step-up verification triggered by risk signals rather than blanket friction
• The trade-off calls. Shipping speed against uncompromising correctness, build against buy. You set the planning cadence with Robbe, you work across Finance, Risk, Ops, and Support, and you are the one who explains upward why a number moved
• The reconciliation automation rate is materially higher than the day you started, and you can show the weekly series
• The exception queue at daily close is worked to zero by a human in under an hour, on a system you built for that
• A new rail or PSP has gone to production on the provider architecture you designed, and it did not require a ledger migration
• Pending, posted, and available are modeled cleanly enough that Support answers "where is my money" off the customer-facing surface instead of escalating to engineering
• Corrections post as reversing entries. Nobody has edited history, and an auditor can say so
• At least one thing you shipped is running with AI in the loop, and the team depends on it
• Finance trusts the close
• Turn a payment provider or bank partner integration spec into a typed client and a test suite in an afternoon instead of a sprint, including the ACH return codes and reversal paths nobody wants to hand-write
• Stand up a rail simulator that produces the failures a sandbox won't: a late return, a duplicate callback, a partial reversal, a webhook that arrives twice out of order, a settlement that lands after the window closed. Then run your ledger against it
• Build an agent that triages the reconciliation exception queue overnight, clusters the breaks, and hands you a ranked list with a proposed cause for each instead of a wall of unmatched rows
• Put an MCP server over the ledger so "where did this discrepancy come from" is a question you ask in plain language rather than another one-off query against a table nobody else understands
• Generate adversarial test cases for the lending and settlement state machines: the repayment that lands mid-default, the partial payment that arrives after a write-off, the return that hits after the payout cleared. Find the transitions nobody specified

Requirements:

• You have owned a double-entry ledger in production. Built one, migrated one, or been the person accountable for one
• You can explain a modeling decision you would make differently now, and why
• You have moved real money on real rails. 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 have handled large transactions, where the failure mode is a five- or six-figure problem and somebody notices immediately
• Database mastery. Expert SQL and relational design, and a transaction that holds under load at auction close and during scheduled auto-pay batches
• Python, Postgres, and AWS are our stack
• You're API-native. Webhooks, idempotency, eventual consistency, and reconciliation are your default vocabulary, not terms you looked up
• You've built real things with AI, not just used it. Agents, skills, MCP servers, connectors, internal tooling people depend on
• Product-owner thinking. You don't just build a pay button. You understand the flow of funds and how to tell a worried customer what happened to their money
• Restraint. The most common way this seat fails is overengineering. You know when a queue and a lambda are the answer and when they are three new partial-failure modes
• We read the work, not the years. Most people who clear this bar have five to ten years behind them, and we have no interest in screening out the person who got there faster
• Backgrounds that fit: payments or ledger infrastructure at a pre-IPO fintech, core banking or money movement at a marketplace, a founding or early engineer who built the money layer, or an infrastructure engineer who took ownership of financial correctness because nobody else would
• You collect, or you have a view on where this market is going
• US-based
• Strong plus: enough React and TypeScript to ship the customer-facing surface that reads off your ledger
• Bonus: distributed systems, credit or risk modeling, direct experience with Stripe, Plaid, Airwallex, PayPal, Modern Treasury, or Increase, evaluating or implementing a third-party ledger service (Modern Treasury, Fragment, Formance, TigerBeetle or similar), stablecoin or on-chain settlement, KYC/KYB, bank partnership, or SOX and audit-readiness exposure