IT Security Tester

Job Title:

IT Security Tester

Location:

Aylesbury

Job Type: Full-Time

Experience

Required:

4-5 Years

Reports to:

Managing Director

Industry: Information Technology / Cybersecurity

We are seeking a skilled IT Security Tester with 4 to 5 years of experience to join our cybersecurity team. The Security Tester will be responsible for identifying and addressing security vulnerabilities across applications, systems, and networks. The role requires a hands‑on professional with expertise in security testing, vulnerability assessments, and secure coding practices, working closely with developers, engineers, and other stakeholders to ensure the overall security posture of the organization.

• Define and maintain test strategy, test plans, and test approach (functional, non-functional, regression, UAT) aligned to project delivery and business outcomes.
• Elicit and review requirements/user stories, ensuring they are testable, clear, and mapped to acceptance criteria and quality gates.
• Design, document, and execute manual test cases covering positive/negative scenarios, edge cases, and data validation checks.
• Develop and maintain automated test scripts (where applicable) to improve test coverage, speed, and repeatability across releases.
• Perform system, integration, and end-to-end testing across applications, APIs, databases, and third‑party integrations.
• Conduct non‑functional testing including performance, reliability, accessibility, usability, and basic security testing in line with organisational standards.
• Manage test environments and test data, ensuring readiness, integrity, and compliance with data protection requirements.
• Log, triage, and track defects in a defect management tool; provide clear reproduction steps, severity/priority assessment, and evidence.
• Work collaboratively with developers and engineers to support root cause analysis, retesting, and verification of fixes.
• Maintain traceability from requirements → test cases → results → defects, ensuring full auditability and coverage reporting.
• Produce and present test execution reports (test metrics, pass/fail rates, defect trends, release readiness) to stakeholders.
• Support release and change processes, including go/no‑go decisions, regression sign‑off, and post‑release quality monitoring.
• Contribute to continuous improvement by refining testing standards, templates, and best practices, and mentoring others where needed.
• Ensure quality practices align with SDLC/Agile/Dev Ops delivery models, participating in ceremonies (refinement, sprint planning, reviews).
• Promote a culture of quality ownership, risk‑based testing, and proactive issue prevention across teams.

• ISTQB Certified Tester – Foundation Level (CTFL)
• ISTQB Agile Tester (Foundation Extension)
• ISTQB Test Automation Engineer (Advanced) (if you do automation heavily)
• ISEB Foundation in Software Testing (UK legacy, still recognised in some places)

• Certified Ethical Hacker (CEH) (broad, recognisable; not purely testing‑focused)
• CompTIA Security+ (good baseline security knowledge for testers)

• Strong analytical skills and attention to detail.
• Excellent verbal and written communication skills.
• Ability to work independently and as part of a cross‑functional team.
• Strong problem‑solving and decision‑making skills in a high‑pressure environment.

• Experience with cloud security testing (AWS, Azure, GCP).
• Knowledge of Dev Sec Ops  practices and tools (e.g., Jenkins, Git, Docker, Kubernetes).
• Familiarity with security frameworks and regulatory requirements (e.g., PCI‑DSS, ISO 27001, GDPR).

• 25 days of holiday, plus the option to buy or sell up to five additional days.
• A competitive salary and comprehensive benefits.
• Continuous learning and development opportunities.

Join Kelltron and contribute to shaping a secure digital future, leveraging our advanced products and services to make a significant impact in the field of cybersecurity.

Please send your resume and cover letter to  with the subject line "Security Tester Application – [Your Name]."