Senior Product Engineer (Backend) - London

About Sequence

If you join Sequence, you will help build the platform that lets companies get paid – we’re already processing $1bn+ in annual invoice volume and growing fast. We are building the AI-powered revenue platform for modern finance teams, replacing fragile spreadsheets and legacy systems with software their teams love using. Cognition, incident.io, MoonPay, and 100+ other high-growth companies trust us to handle their entire revenue cycle across quoting, billing, and revenue recognition. Founded by repeat entrepreneurs, we hit 10x ARR growth last year and just closed a $20M Series A led by 645 Ventures, alongside a16z and exceptional founders and CFOs from companies like Decagon, Klaviyo and Wise.

What’s it like to work at Sequence? Small team, big opportunity, real ownership. You will do work that matters, have direct access to customers, and grow alongside the company. If you want to do the best work of your career at a company that’s scaling fast, we’d love to meet you.

What You’ll Be Doing

We care deeply about the quality of the product we’re building. We’re looking for engineers who are ambitious and take ownership end-to-end: from identifying what to build, through shipping, to making sure it works for real customers. Here’s what you might work on:

• AI-powered approval workflows. Enterprise deals need approval chains, but rigid workflows break when every company has different rules. You will build flexible routing that customers configure in natural language – “require VP approval for deals over $100k with annual terms” – and turn that into deterministic, auditable business logic.
• An intelligent collections agent. Chasing late payments is tedious, manual work. We’re building an agent you instruct in natural language (“send a reminder at 7 days overdue; elevate at 14 days”), which then runs the entire workflow autonomously.
• Scaling billing infrastructure 10x. We’re building revenue-critical infrastructure and currently rearchitecting our billing pipeline for an order of magnitude more throughput – rethinking storage strategies, horizontal scalability, and how we’ll handle 10x load without 10x cost.

We’re a lean team growing to 20+ engineers. You will have real influence on what we build and how we build it. Early enough to shape fundamental architecture. Late enough that customers depend on what you ship. You will design systems that process high-velocity event streams, make technical decisions that balance cost and performance at scale, and build infrastructure that never compromises on reliability. This is business-critical infrastructure: a dropped event means someone isn’t charged correctly. An outage at month-end means finance teams can’t collect revenue from their customers.

What Our Newest Hires Have Shipped

• Watchtower: our command center for AI agents. As we introduce agents that automate financial workflows, customers need visibility and control. This included building our first agent – a contract intake system that extracts customer and pricing information from uploaded or emailed contracts, taking customers from signed contract to automated billing in minutes.
• A fully integrated e-signature experience for quotes. When a customer is closing a deal, friction kills momentum. We rebuilt the signing experience – including embedded authentication and branded emails – into a seamless signing experience used by teams at the top tech companies every day.
• Role-based access controls across the product. Different companies have different structures, but they all need tight control over who can approve deals or access sensitive data. This meant designing a flexible RBAC model that handles resources across every API endpoint and UI surface.

You should apply if:

• You’ve shipped production backend systems and care about the difference between “it works” and “it’s reliable.”
• You care about customers – you want to understand why you’re building something, not just what.
• You’re comfortable with ambiguity. You thrive in early ideation stages, share work-in-progress to gather feedback, and adapt easily based on input.
• You communicate clearly. Thoughtful communication is a superpower that sharpens how we collaborate and build.
• You’re interested in distributed systems and writing resilient software.

Nice to have:

• Deep relational database expertise. We do a lot of complex queries and care about performance.

This might not be right if:

• You enjoy larger organisation structures and staying only within your area of expertise.
• Taking ownership here means doing whatever the problem needs.
• You want a traditional engineering team set up, with a predictable roadmap and clearly scoped out tickets provided for you.
• You prefer a slower pace. Customers are depending on what we ship.
• You aren’t comfortable with production responsibility. We’re revenue-critical infrastructure – on-call matters here.

Tech stack

We hire for ability, not a specific tech stack. Most of the team learned our stack here:

• Backend: Kotlin (modular monolith using Http4k, Spring Boot, Exposed, Result4k)
• Storage: Postgres, BigQuery
• Async messaging: Google Cloud Pub/Sub
• Infrastructure: Google Cloud, Terraform
• Frontend: TypeScript, React
• Monitoring: Google Cloud Monitoring, Sentry
• Tools: GitHub, Slack, Notion, Linear

How We Work

We’re based in London and New York and love spending as much time with our colleagues as possible. We spend three days together in the office, with team lunch on Wednesdays. You will join a cross-functional product team working directly with design and product. We get together twice a year for company offsites.

What we offer:

• Salary: £115,000 - £130,000
• Equity: Meaningful share options
• 25 days holiday + bank holidays
• Modern, flexible pension via Penfold with salary sacrifice available
• Visa sponsorship available

Interview process

We move fast – typically 1-2 weeks start to finish:

• Initial interview (30 mins)
• Technical interview (60 mins)
• Product interview (30 mins)
• System design interview (45 mins)
• Founder interview (30 mins)

We’ve written a detailed blog post about the process with tips about how to prepare.