Senior Backend QA Engineer - API Reliability & Performance

Jobtailor; Greater London; On-site; GBP 55,000 - 90,000; Full time

Job summary

Jobtailor is seeking a backend QA engineer in the Greater London area to design, execute, and maintain test suites for GraphQL and REST APIs. You will verify payloads, status codes, and response times while building automated frameworks in TypeScript or Python.

You will query SQL/NoSQL databases, test distributed microservices (Kafka, RabbitMQ, Pub/Sub), and perform performance and security assessments within an agile team. Collaboration with DevOps is essential.

Qualifications

• 2+ years of dedicated software testing experience focused on backend architecture, API testing, and data integrity.
• Hands-on experience with Postman, REST Assured, or Insomnia.
• Experience querying PostgreSQL, MySQL, MongoDB, or DynamoDB.
• Ability to write and maintain backend test suites in TypeScript or Python.
• Working knowledge of Docker containerization.
• Familiarity with CI/CD pipelines such as GitHub Actions or GitLab CI.
• Excellent root-cause analysis skills.
• Strong technical communication.
• Desirable: performance/load testing experience with k6 or JMeter.

Responsibilities

• Design, execute, and maintain test suites for GraphQL and REST APIs.
• Verify payload structures, status codes, and response times.
• Build and maintain automated backend test frameworks in TypeScript or Python.
• Integrate automated end-to-end tests into CI/CD pipelines.
• Write complex SQL/NoSQL queries to verify data flow and backend consistency.
• Test distributed microservices and asynchronous workflows (Kafka, RabbitMQ, Pub/Sub).
• Conduct performance/load testing with Grafana k6 or JMeter.
• Assess backend security against OWASP API Top 10 and verify JWT/OAuth authentication.
• Use tracing tools and log analysis to isolate breakpoints.
• Collaborate with Developers and DevOps on root-cause fixes.
• Participate in autonomous agile team, prepare test scenarios, support continuous testing, and advocate quality in planning and architecture discussions.

Skills

Backend testing

API testing

Data integrity

Root-cause analysis

Technical communication

Risk identification

Tools

Postman

REST Assured

Insomnia

Docker

GitHub Actions

GitLab CI

k6

JMeter

Kafka

RabbitMQ

Pub/Sub

Job description

Jobtailor is seeking a backend QA engineer in the Greater London area to design, execute, and maintain test suites for GraphQL and REST APIs. You will verify payloads, status codes, and response times while building automated frameworks in TypeScript or Python.

You will query SQL/NoSQL databases, test distributed microservices (Kafka, RabbitMQ, Pub/Sub), and perform performance and security assessments within an agile team. Collaboration with DevOps is essential.