Lead QA Engineer

Lead QA Engineer – Payments / Fintech

Plexus has partnered with a profitable, product-led company building at the intersection of Web3 and payments. Their infrastructure powers some of the largest platforms in crypto and has already onboarded millions of users globally.

We’re looking for a QA Engineer with 3+ years of experience to take ownership of testing across a payments product. The focus will be backend and API testing first, with UI testing second.

Responsibilities

• Test REST APIs, webhooks, signatures, idempotency and payment/order state machines directly.
• Build and maintain automated regression tests for key flows using Playwright or similar, ideally in TypeScript.
• Test payment edge cases including duplicate webhooks, incorrect payment amounts, forged callbacks, reversals and provider outages.
• Own the sandbox environment and test data, including simulated payment providers.
• Carry out load and stress testing ahead of launches.
• Work closely with engineering to identify and test potential failure scenarios.
• Leverage AI tools such as Claude to improve testing workflows.

Requirements

• 3+ years of QA/Test Engineering experience.
• Strong API and backend testing experience.
• Experience with automated testing tools such as Playwright.
• Background in payments, fintech or fiat products.
• Startup mindset with the ability to take ownership.
• Strong English communication skills.
• Crypto familiarity is a plus.