Senior Software Engineer - Billing (VAT & Invoicing)

Location: London

Employment Type: Full time

Department: Engineering

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.

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 customers' pains to design, coding, 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 some of its most significant technical work: migrating tax determination to a third‑party integration, re‑architecting 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's also a growing stream of product‑facing, frontend work as we look to improve the end‑to‑end billing experience.

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.

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: 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 optimisations, testing strategies, and coding standards across the stack.
• Frontend Strategy: Establishes frontend architecture patterns, including state management, performance budgets, and comprehensive testing.
• 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.
• Security & Risk: Oversees operational security, including secrets hygiene and dependency risk management, to ensure a hardened production environment.
• Mentorship & Influence: Levels up the engineering organisation through active mentorship, leading design reviews, and influencing the product roadmap with technical data.
• Cross‑Functional Impact: Coordinates multi‑team deliverables and aligns stakeholders to resolve technical blockers across the organization.
• AI‑Driven Development: Experience with—or a strong interest in—modern AI‑augmented workflows.

How We Work: At Perk, we take an IRL‑first approach to work, where our team works together in‑person 3 days a week. As such, this role requires you to be based within commuting distance of our hubs. For certain roles, we can help with relocation from anywhere in the world. English is the official language at the office. Please submit your resume in English if you choose to apply.

Perk is a global company with a diverse customer base, and we want to make sure the people behind our product reflect that. We’re an equal opportunity employer, which means you’re welcome at Perk regardless of how you look, where you’re from, or anything else that makes you, well, you.