AS400 QA Tester — Payment Systems

About the Role We are building a dedicated in-house payment testing team and are looking for a skilled AS400 QA Tester to join us. This is a specialized role — the right candidate will bring solid AS400 green-screen expertise, an understanding of payment and accounting workflows, and the mindset of someone who naturally thinks through every "what if" scenario before it becomes a problem. Our implementation is highly bespoke, so while domain familiarity is a plus, what matters most is the ability to learn quickly and think critically. Key Responsibilities Operate within the green-screen (5250 terminal emulator) environment to navigate, query, and validate system behaviour. Design and execute test cases that thoroughly cover payment and accounting workflows, including edge cases and failure scenarios. Proactively identify "what if" scenarios — going beyond the obvious to stress-test assumptions and boundary conditions. Log, track, and follow through on defects across the full testing lifecycle. Ramp up quickly on a bespoke payment implementation and apply that knowledge independently. Collaborate with the team to ensure test coverage aligns with business requirements. Document findings and communicate clearly to relevant stakeholders. Required Qualifications Hands-on experience working on IBM AS400 systems. Proficiency operating in the green-screen (5250) environment. Strong analytical thinking — able to independently work through complex scenarios and identify gaps. Fast learner who can absorb new domain knowledge and apply it with minimal ramp-up time. Clear written and verbal communication skills in English. Preferred Qualifications Knowledge of payment processing and/or accounting concepts. Prior experience testing payment or financial systems. What We're Really Looking For Technical skills aside, we need someone who thinks like a detective — not just running scripts, but genuinely hunting for what could go wrong. Someone who's comfortable in ambiguity, takes ownership, and raises issues early. Our domain is specialized and our implementation is unique, so intellectual curiosity and a willingness to dig in matter as much as your technical background.