Senior Software Engineer - Pay Sustainable Engineering

As a Senior Software Engineer on the Pay Sustainability Engineering team, you'll help drive the long-term reliability, scalability, and evolution of our payments, financial and billing ecosystems. The team operates across two complementary tracks. The first focuses on firefighting and platform support, helping engineering teams navigate critical incidents, unblock complex technical challenges, and improve coordination across the broader payment infrastructure. Rather than acting as a delivery team for operational work, you'll provide technical leadership, platform-wide visibility, and guidance that helps teams resolve issues effectively and prevent recurring problems.

The second track focuses on medium- to large-scale sustainability initiatives across the payments domain. This includes identifying technical debt, platform limitations, architectural weaknesses, and product gaps that impact the long-term health of the ecosystem. You'll lead initiatives that improve the resilience, maintainability, and scalability of the platform through thoughtful refactors, system redesigns, and engineering improvements that create lasting impact.

As a senior engineer, you'll play a key role in defining what sustainability engineering means within the Pay organization. You'll partner closely with engineering and product teams to shape the value proposition of the function, prioritise high-impact opportunities, and provide technical direction across complex cross-functional initiatives. Through strong technical leadership, systems thinking, and a focus on sustainable engineering practices, you'll help build a healthier, more scalable payments platform that enables teams to move faster with greater confidence.

At Perk, we know that we feel most fulfilled when we can own the problem and the solution. This means taking responsibility for the entire lifecycle of a feature, from being part in understanding what our customers' pains are with our product team, design documents, coding to deployment, and measuring impact. You will see how your technical decisions move the needle for our customers daily. We prioritise autonomy and pragmatism, giving you the space to solve complex problems without unnecessary friction. Engineering excellence here is measured by the reliability and simplicity of the systems you build to power a global platform.

At Perk, we believe the best work happens when great people come together in small teams, with a shared sense of purpose. You'll join a cross-functional squad where you have real ownership of a piece of Perk's domains, a genuine say in what gets built, and the autonomy to make it happen. Each team decides how to contribute to Perk's company goals. We care about impact, and we trust our people to deliver it.

AI is embedded in how we work and what we build. On the engineering side, it spans the whole workflow: our Notion, Jira, GitHub and Slack are AI-connected so you get up to speed fast, and day-to-day it helps with specifying features, writing and reviewing code, and automated AI PR review on every pull request. When something goes wrong in production, AI surfaces context across systems quickly. We also embrace agentic coding, using AI as an active collaborator, not just a prompt-by-prompt co-pilot. We expect candidates to use AI tools in our coding interviews. The bar is understanding your code and owning what you produce. That reflects how we work every day.

Some examples of what it means to be a Senior at Perk:

• Shape the bigger picture: You won't just build features, you'll refine the what to build and why. At Perk, senior engineers are expected to go beyond the technical solution and focus on the problem itself. You'll contribute to your squad's quarterly goals and long-term vision alongside your Product Manager and Engineering Manager.
• Architect for today and tomorrow: When a big change is needed in how our platform works, you'll be the one writing the design documents that lay the foundation. You'll become a guardian of your team's technical quality; spotting areas of investment, proactively managing technical debt, and making sure we don't let 'busy work' crowd out the work that truly matters.
• Lead across boundaries: Your influence won't stop at your own squad. You'll communicate complex ideas across multiple teams, proactively identify who needs to be involved, and drive alignment across the broader organisation.
• Raise the bar for everyone around you: Senior engineers at Perk are mentors, coaches, and bar raisers. You'll support less experienced colleagues through direct mentorship, thoughtful feedback during reviews, and by modelling what great engineering looks like in practice.

Desired skills and experience:

• Product Leadership: Derives complex business goals into technical roadmaps; de-risks ambiguous projects through spikes and prototyping.
• System Architecture: Architects scalable, evolvable systems and data models that account for performance, failure isolation, and long-term maintenance.
• Technical Standards: Defines and upholds engineering excellence, including CI/CD optimisations, testing strategies, and coding standards across the stack.
• Frontend Strategy: Establishes frontend architecture patterns, including state management, performance budgets, and comprehensive testing (e.g., E2E/Cypress).
• Backend Excellence: Engineers sophisticated backend solutions involving API versioning, caching strategies, and complex data migration plans.
• Operational Maturity: Leads observability and SRE practices; defines SLOs, manages incident responses, and conducts blameless post-mortems.