Senior Backend Engineer, Payments Infrastructure

Location: San Francisco, CA / New York, NY
Company Stage of Funding: Series C AI Infrastructure Company ($10B Valuation)
Office Type: Onsite (5 Days Per Week)
Salary: $130,000–$400,000 + Equity

Company Description

We're representing one of the fastest-growing companies in the AI ecosystem, building the human intelligence infrastructure powering frontier AI models. Their platform connects leading AI labs and enterprises with a global network of experts who help train, evaluate, and improve next-generation AI systems.

As the company scales rapidly, its payments platform has evolved from processing hundreds of thousands of dollars to hundreds of millions in transaction volume. To support continued growth, they are investing heavily in building resilient, observable, and highly automated financial infrastructure that serves as the backbone of their global marketplace.

What You Will Do

• Design and build the next generation of the company's payments infrastructure, supporting large-scale global financial operations.


• Develop highly reliable backend systems that power payout orchestration, settlement processing, reconciliation, and ledger management.


• Build end-to-end observability across payment workflows to proactively detect failures and improve operational reliability.


• Design immutable, auditable ledger systems that ensure financial correctness and long-term scalability.


• Build automation that eliminates manual treasury, payout, and financial operations workflows.


• Architect scalable settlement ingestion and reconciliation pipelines across multiple payment providers.


• Improve resilience, monitoring, and fault tolerance across distributed financial systems.


• Integrate with payment processors, banking APIs, and financial infrastructure providers while maintaining abstraction and portability.


• Partner closely with Engineering, Finance, Product, Operations, and Fraud teams to improve financial system reliability.


• Drive long-term architectural improvements by identifying and eliminating root causes rather than implementing short-term fixes.

Ideal Background

• 5+ years of professional backend or platform engineering experience.


• Strong experience building production systems within payments, fintech, billing, financial infrastructure, or other highly regulated domains.


• Proven expertise developing scalable backend services that prioritize correctness, reliability, and operational excellence.


• Experience integrating payment gateways such as Stripe, Adyen, or similar financial service providers.


• Strong understanding of transactional databases including PostgreSQL or MySQL.


• Experience building distributed systems using Go, Rust, C++, or similar compiled languages.


• Familiarity with messaging platforms such as Kafka, RabbitMQ, Amazon SQS, or comparable event-driven architectures.


• Experience operating large-scale production systems with strong observability, monitoring, and incident response practices.


• Strong systems thinking and ability to balance engineering velocity with long-term reliability.

Preferred

• Experience building ledger systems, reconciliation engines, settlement platforms, or treasury infrastructure.


• Familiarity with Kubernetes, Temporal, workflow orchestration, or distributed systems platforms.


• Experience working directly with banking APIs, ACH, wire transfers, or international payment systems.


• Knowledge of PCI-DSS, payment security, encryption, and financial compliance best practices.


• Experience abstracting payment processors and building provider-agnostic financial systems.


• Background at high-growth fintech companies or infrastructure-focused startups.


• Strong ownership mentality with experience designing systems that operate under significant financial and operational scale.


• Interest in AI infrastructure, marketplaces, and large-scale financial operations.

Compensation and Benefits and Other Things

• Base salary: $130,000–$400,000.


• Generous equity package vested over four years.


• Bi-annual performance bonus structure.


• Up to $15,000 relocation assistance.


• $10,000 housing bonus for employees living within walking distance of the office.


• $1,500 monthly meal stipend.


• Complimentary Equinox membership.


• Monthly wellness and lifestyle reimbursements.


• Comprehensive medical, dental, and vision coverage.


• Opportunity to build the financial infrastructure supporting one of the fastest-growing AI companies in the world.


• Significant ownership over mission-critical systems that directly impact the company's ability to scale globally.


• Work alongside world-class engineers, operators, and AI organizations shaping the future of artificial intelligence.