Senior Software Engineer - Billing Systems & VAT Automation

About Us

Perk (formerly Travel Perk) is the intelligent platform for travel and spend management. Built to tackle the time consuming, manual work that gets in the way of real work, our tools automate everything from travel bookings to expenses, invoice processing, and more. By eliminating this shadow work that wastes hours, erodes morale, and saps innovation, we're on a mission to power real work, with real impact.

We're trusted by more than 10,000 companies worldwide, and we've grown into a global company of 1,800 people across 12 offices worldwide, with headquarters in London and Boston.

Are you a Software Engineer who thrives on real ownership? At Perk, you'll own the entire lifecycle of a feature, from understanding customer pain with product, design and coding to deployment and measuring impact. Your technical decisions will move the needle for our customers daily. We prioritize autonomy and pragmatism, giving you 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 our global platform.

The billing team owns tax determination, invoice issuance, invoice collection, and deferred payments. Current projects include migrating tax determination to a third party integration, rearchitecting invoice issuance for async processing at scale, and automating a manual invoice collection process into a fully self serve service powered by AI. There is also growing product facing, front end work as we improve the end to end billing experience.

At Perk, the best work happens when great people come together in small teams with a shared purpose. You'll join a cross functional squad where you have real ownership of your domain, 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 trust our people to deliver it.

AI is embedded in how we work and what we build. On the engineering side, it spans every workflow—from preparing for meetings and specifications to code reviews and automated AI PR review on every pull request. 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.

Candidates are expected to use AI tools in our coding interviews; the bar is understanding your code and owning what you produce.

• Shape the bigger picture. You will refine the what to build and why, contributing to squad's quarterly goals and long term vision with Product and Engineering managers.
• Architect for today and tomorrow. Write design documents for major changes, guard technical quality, spot investment areas, manage debt, and ensure we invest energy where it counts.
• Lead across boundaries. Communicate complex ideas across teams, drive cross squad initiatives, contribute to engineering guilds, and pair with architects on discovery.
• Raise the bar for everyone around you. Mentor and coach less experienced colleagues, provide feedback during reviews, and lift standards through guild meetings, design reviews, and pairing.

• Product Leadership: Translate complex business goals into technical roadmaps; de risk ambiguous projects through spikes and prototypes.
• System Architecture: Architect scalable, evolvable systems and data models that consider performance, failure isolation, and long term maintenance.
• Technical Standards: Define and uphold engineering excellence, including CI/CD optimizations, testing strategies, and coding standards across the stack.
• Frontend Strategy: Establish frontend architecture patterns, state management, performance budgets, and comprehensive testing, including E2E/Cypress.
• Backend Excellence: Engineer sophisticated backend solutions involving API versioning, caching strategies, and complex data migration plans.
• Operational Maturity: Lead observability and SRE practices; define SLOs, manage incident responses, and conduct blameless post mortems.
• Secu…