Staff Full-Stack Engineer, Payments Infrastructure

Sapiom; San Francisco (CA); On-site; USD 180,000 - 260,000; Full time

Job summary

Sapiom in San Francisco is seeking a Staff Software Engineer to lead a core payments platform used by AI agents to buy, pay, and reconcile with merchants. You will focus on reliability, security, and scalable design for complex checkout flows and payment rails.

You will own architecture from first principles, defend trade-offs, and ship interfaces that other engineers build on. This is a multi-quarter, high-impact role that leverages AI tooling to improve engineering workflows.

Qualifications

• 8+ years building production software, several in payments, money movement, or financial infrastructure.
• Ownership of architecture from first principles, including design and cost considerations.
• Experience designing for failure: idempotency, retries, reconciliation across systems.
• Strong TypeScript skills and ability to build interfaces atop your own system.

Responsibilities

• Limits and authority: determine how much latitude to give an agent and enforce before money moves.
• Completing the purchase: ensure checkout is reliable across many merchants and scenarios.
• What happens when it goes wrong: diagnose what happened before acting, avoid double charges.
• Proof: maintain versioned, legible records of what buyers saw and agreed to.
• The surface customers build on: design the public API and tools an agent uses, and ensure correct contract modeling.

Skills

Production software

Payments

Money movement

Financial infrastructure

TypeScript

System architecture

Resilience

AI tooling

Job description

Sapiom in San Francisco is seeking a Staff Software Engineer to lead a core payments platform used by AI agents to buy, pay, and reconcile with merchants. You will focus on reliability, security, and scalable design for complex checkout flows and payment rails.

You will own architecture from first principles, defend trade-offs, and ship interfaces that other engineers build on. This is a multi-quarter, high-impact role that leverages AI tooling to improve engineering workflows.