Senior SDET (Software Development Engineer in Test) at Fullscript – Ottawa, Illinois

The Core Payments team is the revenue engine powering Fullscript’s growth.

We own the end-to-end ecommerce experience, including cart, checkout, payments, taxes, discounts, payouts, and financial reporting. Every transaction flows through these systems, requiring high reliability, security, and correctness.

We’re hiring a Senior SDET to own the engineering of quality for revenue-critical payment systems. This role focuses on building and evolving automated testing systems, improving developer workflows, and ensuring quality is enforced through engineering practices and not just manual validation.

• Own the design, development, and maintenance of scalable automated test frameworks (Playwright, API, integration, end-to-end)
• Build and operate reliable test infrastructure integrated into CI/CD pipelines
• Drive test automation strategy, optimizing for coverage, speed, and signal quality
• Identify systemic quality gaps and address them through tooling and engineering improvements
• Partner with engineers to design systems for testability (e.g., observability, contracts, idempotency)
• Write production-quality code for test systems, utilities, and supporting infrastructure
• Improve developer experience by enabling fast, reliable feedback loops
• Validate complex payment flows and external integrations (e.g., Stripe) through automation-first approaches
• Lead root cause analysis for defects and implement systemic fixes to prevent recurrence
• Define and enforce quality standards for high-reliability, revenue-critical systems

• 5+ years of experience in software engineering, SDET, or test automation roles
• Proven experience designing and maintaining test automation frameworks at scale
• Experience with API, integration, and end-to-end testing patterns
• Strong understanding of CI/CD systems and test pipeline optimization
• Experience improving test reliability, performance, and maintainability
• Ability to design systems for testability (e.g., dependency injection, contract testing)
• Experience working with distributed systems and understanding failure modes
• Experience with payments, e-commerce, or financial systems (preferred)
• Strong collaboration skills and ability to influence engineering practices

• Generous PTO and competitive pay
• Fullscript’s RRSP match program for financial health
• Flexible benefits package and workplace wellness program
• Training budget and company-wide learning initiatives
• Discount on Fullscript catalog of products
• Ability to work Wherever You Work Well*

Why this role matters

This team owns systems where defects directly impact revenue, financial accuracy, and customer trust. This role ensures quality is engineered into the system—preventing issues before they reach production and enabling safe, reliable delivery at scale.