Senior Backend Engineer – Growth

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 powers the next generation of cross-border payment systems for institutions.Our early team comes with experience from J.P. Morgan, Goldman Sachs, FalconX, PayPal, Affirm, Polygon, Kraken, and Nium, and we’re backed by Accel, Lightspeed, NfX, and other top-tier investors.

As a Backend Engineer on the Growth Pod, you will design and build backend systems that power customer onboarding, activation flows, lifecycle tooling, and growth experiments. This role goes beyond traditional backend engineering: you’ll combine strong system design skills with a data-driven growth mindset, ensuring that every customer interaction generates trusted data and actionable insights.

Your work will directly enable Product and Go-To-Market teams to understand users better, reduce friction in activation, and run experiments that drive sustainable growth.

Backend Engineering & Systems

• Build and maintain backend services that support customer onboarding, KYC/KYB, and activation flows.
• Develop APIs and event-driven systems that reliably capture customer interaction data across the funnel.
• Ensure backend systems are secure, reliable, and scalable to support rapid growth and experimentation.

Data-Driven Growth Enablement

• Design systems that make customer interaction data accessible and actionable for Product, Growth, and GTM teams.
• Implement clean, standardized event instrumentation across backend services.
• Partner with Data Engineering to ensure consistent pipelines into BigQuery and analytics layers.
• Build APIs and integrations that connect backend systems to growth/marketing tools (Heap, RudderStack, Customer.io, HubSpot).

Experimentation & Customer Impact

• Enable the Growth Pod to run A/B tests and lifecycle experiments, ensuring correct backend event capture and reporting.
• Create tooling that accelerates experimentation (e.g., feature flags, sandbox environments, rapid test APIs).
• Deliver backend features and data integrations that directly improve activation funnel performance (reducing drop-offs, speeding time-to-value).

• 3–5 years as a Backend Engineer in high-growth tech/fintech environments.
• Strong proficiency in backend languages (e.g., NodeJS, TypeScript) and API design.
• Experience building event-driven systems and working with databases at scale.
• Exposure to growth or marketing technology systems (Heap, RudderStack, Customer.io, HubSpot, Segment, etc.).
• Strong understanding of event tracking and data instrumentation across customer interfaces.
• A data-driven mindset — ability to translate customer interaction data into actionable insights for Product and GTM.

• Prior experience in growth engineering or backend systems designed for activation and experimentation.
• Familiarity with feature flagging and experimentation platforms (LaunchDarkly, Optimizely).
• Knowledge of compliance and security requirements for onboarding and payments.
• Experience supporting customer journey analytics, lifecycle messaging, or funnel optimization.

• Competitive salary and benefits package.
• Equity in a rapidly growing company.
• Opportunity to shape customer-facing systems and growth experiments at scale.
• A collaborative culture with strong ties across Product, Growth, Engineering, and GTM.
• Professional development within a world-class fintech team.

We are committed to building a diverse and inclusive workplace. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, disability, or veteran status.