Founding Engineer - Payments

PayOS | San Francisco | $150k – $200k + Equity

The Mission

AI agents are ready to run the economy, and PayOS is readying the financial infrastructure for it.

The Opportunity

We are looking for a Founding Payments Engineer. We need you to own the Payments Layer for PayOS - the connective tissue between our platform and the payments ecosystem of networks, acquirers, processors, and issuers. This is a role for a deeply experienced builder with 7–10+ years in payments who knows how the ecosystem actually works from the inside, and who wants to define how AI interfaces with payments.

• Do you know the card networks at the API and message level, not just conceptually?
• Have you lived on both sides of the ecosystem - acquiring and issuing?
• Have you shipped merchant-facing payment products that real businesses depend on?
• Do you feel like you have it in you to be a General Manager of what you will build - build, sell, support?

If yes, please apply immediately.

Your Stack & Responsibilities

• Own the Payments Layer: You will design and build how PayOS connects to and orchestrates the payments ecosystem — integrations, transaction flows, payment credentials, and the domain logic that makes agentic commerce safe and correct.
• Ecosystem Depth (Issuer, Acquirer, or Network): You have deep, hands-on experience in at least one side of the payments ecosystem and ideally more than one:
  • Network: Direct integration with card network APIs (Visa, Mastercard), ISO 8583 / ISO 20022 message flows, network tokenization, and certification/compliance releases.
  • Acquirer/Processor: Merchant onboarding, transaction routing, auth flows, interchange and fee logic, chargebacks, and settlement. You know where the bodies are buried in a processor integration.
  • Issuer: Card issuance, authorization decisioning, BIN sponsorship relationships, and program management.
  • Merchant-Facing Payments: You have shipped merchant-facing payment products and understand what merchants actually need: reliable auth rates, clean reconciliation, transparent fees, fast settlement. Reliability & Correctness: In payments, 99.9% isn't enough. You build idempotent, auditable flows and design for PCI-DSS compliance and regulatory scrutiny from day one. AI-Leveraged Building: We maximize leverage by embracing AI. You generate code using Claude, Gemini, ChatGPT and other models/tools to amplify your output far beyond what is typically possible for a single person - while applying the judgment that only years of hands-on payments experience gives you. Forward-Deployed Engineering: You will frequently partner with customers to integrate our platform, debug production flows alongside them, and build workflows that prove the value of PayOS.

Our DNA (Who You Are)
Passion & Agility (High Intensity): We move incredibly fast. We are a team that does "whatever it takes" to move the needle. This often means working with high intensity and being responsive outside of traditional hours because we are deeply invested in our mission - and because payments never sleep.

Concrete Outcomes > Activity: We don't care about "effort"; we care about solving our customers' problems and building the services they need. You measure your success by the concrete value you bring to the company every day. You ship systems that handle money correctly, not just code that looks good.

Deep Product & Market Fluency: You must go beyond the code. You need to deeply understand the payments landscape - networks, processors, issuers, regulators. Success here means identifying customer gaps and architecting solutions that resonate immediately.

Ownership & Autonomy: We don't have playbooks. You are a self-learner who spots a problem and solves it immediately without waiting for instructions. You roll up your sleeves and wear multiple hats.

One Team, Zero Politics: Because we are small, chemistry is everything. We prioritize total transparency. If you face a roadblock, you share it early. We view challenges collectively: an issue you face is an issue for all of us.

Requirements
7–10+ years of software engineering experience, with the majority in payments
Deep experience in at least one of the following (more than one is a strong plus):
* Card network APIs and message specifications (ISO 8583 and/or ISO 20022)
* Acquirer/processor systems: onboarding, routing, auth, interchange, disputes, settlement
* Issuer systems: authorization, card programs, BIN sponsorship
* Experience shipping merchant-facing payment products
* Strong systems engineering fundamentals: distributed systems, idempotency, auditability
* Working knowledge of PCI-DSS and payments compliance/regulatory requirements

Benefits & Perks

• Top-Tier Healthcare: 100% Employee-Covered Health, Dental, and Vision insurance.
• Meaningful Equity: You are joining the Founding Team.
• Cutting Edge: Work on the absolute frontier of Fintech x AI.

How to Apply

We do not want a standard cover letter. Please send an email to [email protected] with:

Your GitHub/Portfolio (or a summary of payment systems you've built and operated).
A description of a payments integration or product you owned end-to-end — scale, architecture, and your specific role.