Software Developer Engineer in Test (SDET)

Sound Decisions Recruiting is posting this role on behalf of an unnamed client that builds merchant payment technologies. The SDET will own the quality layer of the client’s AI-assisted delivery pipeline, building automated tests and CI/CD quality gates while shaping the team’s quality strategy.

Responsibilities:

• Design and build an automated test framework across API, integration, UI (React) and data layers
• Integrate automated suites into CI/CD as quality gates, with fast feedback on every pull request and full regression before release
• Build AI into the QA pipeline:
• LLM-generated test cases from requirements and API specs
• Self-healing UI locators
• AI-assisted failure triage and flaky-test detection
• Risk-based test selection driven by what changed in each commit
• Write deep API and contract tests for the payments and rules engine, covering jurisdiction and card-brand combinations, rounding, currency and edge cases
• Build test-data and environment tooling, including synthetic transactions, seeded PostgreSQL states and mocked processor responses
• Add performance testing for real-time, pre-authorization calls where latency matters
• Track and report quality metrics (coverage, escape rate, flake rate, time to detect) so leadership can see release readiness
• Take part in planning and refinement early, and write testable acceptance criteria before code is written
• Use AI tools to accelerate research, test design, coding, debugging and documentation while validating all generated output
• Follow the concepts of an agile process, including iterative delivery, prioritization and continuous improvement

Requirements:

• 4+ years as an SDET, test automation engineer, or software engineer with heavy test-framework ownership, or equivalent demonstrated proficiency
• Production-quality coding in C#/.NET, TypeScript/JavaScript, or Python
• Hands-on experience building UI and API automation with modern frameworks (Playwright, Cypress, Selenium) and REST/API testing (RestSharp, Postman/Newman, REST Assured, Pact or similar)
• Experience wiring automated suites into CI/CD (GitHub Actions, Azure DevOps, GitLab CI, Jenkins) as quality gates, with parallelization and reporting
• Real, recent use of AI in testing, for example: • LLM-generated test cases from specs or stories • AI-assisted failure triage or flake detection • agentic test runners • Claude, Copilot or Cursor workflows built into a test pipeline
• Solid SQL, and comfort validating data directly in PostgreSQL or similar
• The instinct to break things: boundary values, non-happy paths and combinatorial rule testing
• Experienced at managing your time and accountable for your actions
• Great at communicating: • Polished writing and speaking in all communication channels • Writing bug reports that let an engineer reproduce the issue on the first try • Explaining quality risk and release tradeoffs to engineers, product and business counterparts
• Able to work with minimal supervision, balance multiple activities and meet deadlines
• Operating with integrity. Green builds mean something because you never fake them
• Being able to quantify knowns and unknowns, including what is covered, what isn't, and the risk of each
• Strong sense of risk awareness, especially where money and compliance are involved
• Always learning new tools, and testing them before trusting them
• Great at code reviews, especially on test code, delivering criticism in a constructive and helpful way
• Payment, card processing, billing, financial or e-commerce domain experience
• Building or testing MCP servers, LLM evaluation harnesses or AI agents
• Contract testing, service virtualization, or testing rules and calculation engines
• Performance and load testing (k6, JMeter, Gatling)
• Exposure to Scala or another functional language
• Docker/Kubernetes test environments and cloud (GCP/Azure)
• Compliance-aware testing (PCI DSS, SOC 2)
• Prior experience in a startup or similarly fast-moving environment