Senior Backend QA Engineer – Fintech & API Automation

BUX B.V.; Amsterdam; On-site; EUR 70,000 - 110,000; Full time

Job summary

BUX is seeking a Senior Quality Assurance Engineer (Backend) in Amsterdam to own quality across our backend services. You’ll design, implement, and maintain automated tests for REST APIs, while executing manual testing where needed and maturing QA processes within the squad.

You will collaborate with Product, Dev, and DevOps, ensuring data integrity and regulatory compliance in a fast-paced fintech environment.

Qualifications

• 5–7+ years of software quality assurance in fintech.
• Strong hands-on manual and exploratory testing with test automation.
• Proficiency in API testing (REST) and microservices architectures.
• Hands-on experience with test automation frameworks such as Selenium and Playwright with TypeScript.
• Proficiency in at least one programming language (Java/Kotlin)
• Understanding of CI/CD pipelines and integration of automated tests (GitHub Actions)
• Practical experience with Postman/Newman, Charles Proxy, and Xray (or similar test management tooling)
• Comfortable validating data across multiple database technologies and asynchronous event flows
• Experience helping establish or mature QA processes within a squad or team
• Experience working in a fast-paced Agile environment
• Excellent communication and collaboration skills with cross-functional teams
• This role reports to the Staff QA Engineer

Responsibilities

• Design, implement, and maintain automated tests for backend REST services
• Execute manual and exploratory testing where automation isn't feasible
• Help build and mature QA processes, standards, and definition of done within the squad
• Apply quality gates and acceptance criteria in close collaboration with Product and Development teams
• Participate in design reviews for owned backend features to provide a QA perspective early in the development cycle
• Monitor and track key quality metrics, test coverage, and defect trends for backend services
• Perform bug triage, reproduction, and prioritisation with development teams
• Integrate automated regression, smoke, and integration test suites into CI/CD pipelines (GitHub Actions)
• Support test environment setup, data provisioning, and maintenance in coordination with DevOps
• Use approved GenAI tooling with sanitised data to accelerate test design and automation, subject to human review, security policies, and validation of generated tests

Skills

Manual testing

Automation testing

API testing (REST)

Fintech domain

Java/Kotlin

CI/CD

GitHub Actions

Selenium

Playwright

TypeScript

Communication

Tools

Selenium

Playwright

Postman/Newman

Charles Proxy

Xray

Job description

BUX is seeking a Senior Quality Assurance Engineer (Backend) in Amsterdam to own quality across our backend services. You’ll design, implement, and maintain automated tests for REST APIs, while executing manual testing where needed and maturing QA processes within the squad.

You will collaborate with Product, Dev, and DevOps, ensuring data integrity and regulatory compliance in a fast-paced fintech environment.