Software Engineer, Payments Infrastructure

Payments Infrastructure Engineer

The Payments Infrastructure team builds the trust boundary between a live conversation and the rest of Sierra: sensitive data enters through a customer's voice or chat, leaves as a token, and the agent never sees the plaintext in between. Doing this well means weaving four hard domains together at once: LLMs, payments, infrastructure, and voice. Done right, it unlocks seamless, compliant payments for every Sierra agent and the people who use them. It's already one of the highest-containment features Sierra ships: when an agent can take a payment, the conversation keeps going instead of transferring to a person, so the agent resolves everything around it too. The platform is PCI DSS Level 1, on Visa's Global Registry, and carries cardholder data across millions of payment lifecycle events for enterprise customers.

Design the secure-capture protocol every channel sits behind, so the payment feels like one continuous conversation to the person on the other end, while telephony providers, contact-center platforms, embedded chat, and Sierra's own voice stack all present a single event lifecycle to agent code, no matter how different each customer's stack is.

Build and extend the tokenization platform: per-token envelope encryption with a unique data key per token, so a single compromised decrypt exposes one token at most.

Own the security perimeter around the cardholder-data environment, so what each system can reach is enforced by infrastructure rather than convention, and auditable by design.

Build deterministic, auditable detection in the agent's hot path that catches the cardholder data general-purpose models miss, and help design the purpose-built detection model that comes next. No LLM, including any we build ourselves, ever sees plaintext cardholder data.

Make payments something other engineers can use without becoming compliance experts: drive the platform toward processor-agnostic charging, self-serve onboarding, and single-tenant deployments, so a team can add payments to an agent without a payments infrastructure engineer in the loop.

Set technical direction across the team's hardest problems, get the abstractions right so we solve each one once rather than per customer, and raise the bar for the engineers around you.