Senior Software Engineer - Billing

About Us

Perk (formerly TravelPerk) 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, including Wise, On Running, Breitling, and Fabletics, and we’re tackling the 7 hours of lost productivity per employee each week, a $1.7 trillion problem. Founded in 2015, Perk has grown into a global company of more than 1,800 people across 12 offices globally, with headquarters in London and Boston. We combine innovation, control, and simplicity to transform how businesses work and how people feel at work. At Perk, we’re driven by our values, like being an owner, delivering a 7-star experience, and working as one team. We value curiosity, purpose, and mindset, not just knowledge, to unlock the power in your potential. Our talent team brings together leading minds from the travel and SaaS industries, representing over 70 countries. If you’re excited about having a real impact and shaping how millions of people experience work, we’d love you on the team.

Are you a Software Engineer who thrives on real ownership? 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 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 prioritize 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.

Join the Billing team

The billing team owns tax determination, invoice issuance, invoice collection, and deferred payments. Right now the team is in the middle of significant technical work: migrating tax determination to a third-party integration, rearchitecting invoice issuance for async processing at scale, and automating a previously manual invoice collection process into a fully self-serve service, with AI at its core. There is also a growing stream of product-facing frontend work as we look to improve the end-to-end billing experience. If you want real ownership of a domain that matters, in an engaged team that values teamwork, this is the team.

How we work

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 at Perk

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. At Perk, we believe in impact over effort: our customers see results, not the hours behind them. Your job is to make sure we're always investing our energy where it counts most.
• 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. Whether it's coordinating a cross-squad initiative, contributing to one of our engineering guilds (where engineers from different teams align on shared technical topics), or pairing with architects on solution discovery, you'll operate comfortably beyond your immediate team.
• 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. You'll help Engineering Managers understand where the team needs to grow technically, and you'll use spaces like guild meetings, design doc reviews, and pairing sessions to lift the overall standard. At Perk, we are a team, and the team's success is your success.

Desired skills and experience

• Product Leadership: Translates 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 optimizations, 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.