Principal Software Engineer, AMER Payments

Trustly•San Francisco, CA

2d•Hybrid

About The Position

Trustly is seeking a Principal Software Engineer for its AMER Payments organization. This is a hands-on engineering role focused on owning the code and contracts connecting payments systems, bank connectivity, and risk decisioning. The role is expected to spend about two-thirds of its time building and to personally deliver the hardest cross-system changes. The engineer will own versioned specifications and contract tests for cross-domain systems, contribute to the global API specification, and lead technical responses to cross-domain P0 and P1 incidents as part of an escalation rotation. The role also runs peak-event readiness activities, including load tests, failure drills, and capacity decisions, and leads the US Platform squad by setting platform priorities and contracts in collaboration with business squads and Core Payments TPMs. The position is hybrid and based in Trustly’s San Francisco office, with team members expected in the office Tuesday through Thursday.

Requirements

Typically 15 or more years of software engineering experience, with principal-level scope across multiple teams while continuing to write production code.
Experience designing, building, and operating payment, banking, or ledger systems at scale.
A record of setting technical direction through code and clear writing.
Product judgment and ability to make platform trade-offs with business and product leaders as well as engineers.
Deep distributed-systems expertise, including consistency, idempotency, concurrency, and failure handling.
Practical, current use of AI in engineering, with clear judgment about its limits in regulated systems.

Nice To Haves

Experience with ACH, RTP, FedNow, or open banking.
Experience unifying platforms across regions.

Responsibilities

Write and merge code on the critical path every week, including reference implementations, contract tests, and difficult fixes.
Own versioned contracts between payments, bank connectivity, and risk, with contract tests in CI that fail the build if a contract breaks.
Build the first version of difficult cross-domain changes and hand them off to the owning team.
Own the global API specification in collaboration with engineers responsible for merchant-facing APIs.
Lead the technical response to P0 or P1 incidents that cross domains as part of the escalation rotation.
Run peak-event readiness, including load tests, failure drills, and capacity calls.
Lead the US Platform squad by setting platform priorities and contracts across payments, bank connectivity, and infrastructure, balancing them against business-squad needs with program support from Core Payments TPMs.