Senior Backend Engineer (L3) - Payments

About Us

OpenFX is on a mission to move money as freely as data, unrestricted by time zones, banking hours, or legacy systems. We are building the infrastructure that will power the next generation of cross-border payment systems for institutions. The team's execution has been exceptional, and we're scaling at a remarkable pace. Our stellar early team comes with experience in companies like J.P. Morgan, Goldman Sachs, FalconX, PayPal, Affirm, Polygon, Kraken, Nium others. We're backed by Accel, Lightspeed, NfX and other top-tier investors.

Role Overview

We're hiring a backend-heavy Full Stack Engineer for our Payments team — the team that owns how money actually moves for our clients.

Payments owns corridor expansion (EUR, MXN, COP, AED, and beyond), the operationalization of our EU licenses (safeguarding of customer funds, transaction monitoring), and the payments product across GUI and API. Our north star is payment volume moved reliably, with corridor success rate and on-time settlement as the control metrics.

You will own the systems on that money path. This is where a client's payment gets initiated, routed to the right partner, tracked through cut-offs and settlement, and reconciled — and where a failure is not a bug ticket but stuck money. You will own the backend of these flows — partner integrations, payment lifecycle state machines, webhooks, retries, and idempotency — and be trusted with the correctness of what actually happens to the money.

You will also work across the stack. The payments product ships on both API and GUI surfaces, and you'll build the dashboard views your backend powers — payment status, tracking, reporting — rather than waiting on someone else to unblock you. You don't need deep frontend expertise for this role, but you do need to be genuinely comfortable there.

We're specifically looking for someone with a payments or fintech background. Think a payment gateway, PSP, neobank, or cross-border payments company (Razorpay, Juspay, Cashfree, PhonePe, Nium, or similar).

Key Responsibilities

• Own the backend of critical payment flows — initiation, partner routing, lifecycle state (statuses, webhooks, returns, recalls), and settlement tracking — across API and GUI surfaces.
• Build and extend partner integrations for new corridors: adapters for banking and payment partners, cut-off and calendar handling, and reconciliation hooks from day one.
• Design for correctness under failure — idempotency, safe retries against external partners, exactly-once effects on money state, and graceful degradation when a partner is down.
• Contribute to the engineering of regulated controls: safeguarding flows and transaction monitoring pipelines, with audit trails built in rather than bolted on.
• Build the client-facing surfaces your backend powers — payment tracking, status views, and reporting in the dashboard — and ship features end-to-end rather than stopping at the boundary.
• Instrument the money path — payment success rates, stuck-payment detection, partner latency and error rates — so problems are visible before clients or partners report them.
• Partner closely with Product to shape flows, and with senior engineers to shape API contracts and corridor architecture.
• Drive work to closure with Product, Operations, and Compliance. You are accountable for adoption, not just delivery.
• Act as a product engineer — scope a problem statement, understand its product impact, and take the hard prioritisation calls.
• Raise the bar through code review and design feedback, and mentor L1/L2 engineers on the team.
• Build a healthy engineering-excellence and tech-debt backlog — surface the right items, work with the EM on a resolution plan, and drive them to closure.
• Participate in on-call, respond to incidents with urgency — on the money path, urgency is literal — and turn post-mortems into durable fixes.

What we are looking for

Must-haves:

• 5–7 years of experience building production backend systems, with the majority of that depth on server-side and distributed systems work.
• A payments or fintech background — you've worked at a payments company, gateway, PSP, or bank-facing fintech and have built systems on a live payment or money path (e.g. Razorpay, Juspay, Cashfree, PhonePe, Nium, or similar).
• Deep expertise in TypeScript and Node.js , and strong command of designing and operating REST APIs on non-trivial systems.
• Strong data modelling and query skills on PostgreSQL — schemas for money state, transactional integrity, and queries that stay correct and fast as volume grows.
• Sound instincts for correctness under failure — idempotency, retries against external systems, partial failures, ordering, and duplicate handling. You've been burned by at least one of these and design differently because of it.
• Hands-on experience integrating external partner APIs — auth schemes, certificates, webhooks, sandbox-vs-production drift, and partners whose failure modes are undocumented.
• Experience with asynchronous processing — queues, jobs, or workflow engines — for long-running, multi-step flows.
• Experience writing automated tests for backend systems, including integration tests against flaky external dependencies.
• Working frontend proficiency: building React views on your own APIs, comfort in a Next.js (or similar) codebase. You should be able to own the GUI surface of your own feature.
• Solid command of object-oriented programming principles and low-level design patterns.
• Comfort with abstract, ambiguous problems — you can turn a vague mandate into scoped, sequenced deliverables without waiting for someone to specify it for you.
• Hands-on and high agency. You find the important problem and go solve it rather than waiting to be assigned it.
• Heavy AI user. You use AI coding tools with real technique and get materially more done because of it.
• Data-driven , and a clear written communicator — we are async-heavy and globally distributed.

What helps you stand out:

• Exper