Staff Software Engineer, Full Stack (Agentic Payment)

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

About Sapiom

Sapiom is building payment infrastructure for AI agents. We enable agents to make purchases for people, manage payments between businesses, and buy the compute, inference, and APIs they need to operate.
Through one integration, Sapiom connects agents to funding sources and payment methods. Our intent verification checks that each transaction matches what the person or business authorized. Spending controls define where and how much agents can spend, with a record of every transaction and its outcome. We're building toward a world where people and businesses can delegate payments to agents with confidence.
We're a small team in San Francisco with deep experience in payments and infrastructure. Our founder was Director of Engineering in Payments at Shopify for five years. We've raised $50 million in our first 12 months from Accel, Dragonfly, Coinbase Ventures, Okta Ventures, Menlo Ventures and Anthropic.

About the role

Agents are starting to buy things on their own, and the rails underneath all assume a person at the keyboard. Letting an agent complete a purchase inside limits its owner actually set, and keeping proof of what was agreed, is the company.

The first version of that ships before you'd start. Almost everything that turns it into something customers can depend on is still ahead, and the team works those problems in parallel rather than one at a time. You'd own one of them.

Payments is unforgiving in a way most product work isn't. A purchase either moves money or it doesn't. A record either holds up six months later when someone disputes a charge, or it's worthless. We'd like someone who finds that interesting.

This is a staff role. You'd set the design for a large piece of this, at thirty people, while it's still deciding-shaped.

What you'd work on

Limits and authority. How much latitude an owner hands an agent, and how that gets enforced before money moves rather than explained afterwards. Most of these decisions are still open.

Completing the purchase. Checkout is where this gets unglamorous. Every merchant behaves differently, totals move, and plenty of steps still expect a human. Making that reliable across a long tail of them is a multi-quarter problem.

What happens when it goes wrong. A payment that goes quiet is the hardest case in the domain. The system has to work out what actually happened before it does anything else, and never charge someone twice.

Proof. A versioned record of what a buyer saw and agreed to, still legible months later when someone disputes it. Unglamorous, and the thing the rest of it rests on.

The surface customers build on. A public API and the tools an agent calls. Designing a contract a model uses correctly is its own discipline.

You may be a fit if

• You have 8+ years building production software, several of them in payments, money movement, or financial infrastructure. We're hiring for depth in the domain.

• You've owned architecture from first principles — set the design, defended it, and lived with what it cost.

• You've worked somewhere being wrong was expensive, and you design for failure up front: idempotency, retries, reconciliation against a number someone else is also computing.

• You have real range across the stack. Strong TypeScript, and you build the interface on top of your own system instead of handing that off.

• You've run a multi-month project from a problem statement rather than a spec, and other engineers built on what you shipped.

• You use AI tools in your own engineering workflow.

Nice to have: card issuing, tokenization, or PCI scope; checkout integrations at depth; browser automation or request interception; something you shipped that an LLM calls as a tool; early-stage companies where you set the architecture rather than inherited it.

Applying

Everyone on our engineering team carries the title Member of Technical Staff internally.