Senior Software Engineer (UK)

Sequence HQ; Greater London; Hybrid; GBP 90,000 - 110,000; Full time

Job summary

A cutting-edge tech company is seeking software engineers to develop robust backend systems and event-driven architectures. Candidates will own revenue-critical infrastructure and contribute to significant architectural decisions to support the growth of B2B billing solutions. This position encourages collaboration in a dynamic environment while delivering innovative solutions that prioritize data accuracy and system performance. A competitive salary range of £90,000 to £110,000 plus share options is offered, with a flexible working arrangement.

Benefits

Salary range of £90,000 - £110,000

Share options

Influence on architectural decisions

Collaborative team culture

Flexible remote work options

Qualifications

• Strong experience in backend systems that handle significant load.
• Experience with event streaming platforms and architectures.
• Knowledge about analytical databases or OLAP systems.
• Provisioning cloud resources and writing infrastructure-as-code.
• Familiarity with strongly-typed languages, ideally Kotlin.

Responsibilities

• Own revenue-critical event infrastructure.
• Design scalable data systems and event streaming pipelines.
• Shape backend architecture and set technical standards.
• Build for future scalability as the company grows.
• Collaborate within a small, agile engineering team.

Skills

System scaling

Event-driven architectures

Data systems knowledge

Infrastructure ownership

Backend coding in strongly-typed languages

Adapting in uncertainty

Customer-centric approach

Job description

The role

We're looking for software engineers with strong backend and cloud infrastructure experience to build the systems that power billing for modern B2B companies.

You’ll own revenue‑critical infrastructure – the kind where correctness isn’t negotiable and downtime isn’t an option. Our usage events platform processes every merchant action that determines how their customers get billed, making it one of the most critical systems we run. You’ll work on the evolution of this platform to handle exponential growth while maintaining perfect accuracy.

This is a rare opportunity: you’re joining early enough to make fundamental architectural decisions, but late enough that real customers depend on what you build. You’ll 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.

What you’ll do

Own revenue‑critical event infrastructure. You’ll work on systems that process customer usage data on which billing and invoicing depend. Design event streaming pipelines that handle high throughput with low latency. Build robust systems where data accuracy is non‑negotiable and uptime is measured in nines.

• Design scalable data systems. You’ll work with event streaming architectures, building sophisticated ingestion pipelines and query optimization strategies. Our event volumes grow with every new customer, so you’ll architect systems that scale efficiently while keeping costs reasonable.
• Shape our backend architecture. You’ll tackle our most complex technical challenges and set the standards for how we solve them. Our services run on Kotlin with Spring Boot, and you’ll have significant influence over architectural patterns and how we approach infrastructure problems.
• Build for the next phase of growth. You’ll design systems that work beautifully today and scale to 10x the load tomorrow. This means thinking about data storage strategies, horizontal scalability, and how your architectural decisions affect performance as volume increases.
• Drive impact on a small team. We’ve built an engineering culture around collaboration, learning, and shipping. You’ll have significant influence on what we build, how we build it, and how we work together.

This is a great fit if you…

• ✅ Love building systems that scale. You’ve worked on backends that handle significant load and understand the tradeoffs in designing for throughput, latency, and cost. You know when to optimize and when good enough is actually good enough.
• ✅ Have strong experience in event‑driven architectures. You’ve built pub/sub systems, worked with event streaming platforms, and understand the nuances of event delivery semantics, backpressure, and ordering guarantees.
• ✅ Think deeply about data systems. You’ve worked with analytical databases or OLAP systems. You can reason about columnar storage, indexing strategies, and query optimization without needing a whiteboard.
• ✅ Own your infrastructure. You’ve provisioned cloud resources, written infrastructure‑as‑code, and made architectural decisions that balance competing constraints. You understand how to model and optimize costs as systems scale.
• ✅ Write backend code in strongly‑typed languages. Our services run on Kotlin, though you don’t need prior experience – many of our engineers learned it here and loved the challenge. What matters is that you’re comfortable with type systems and backend development.
• ✅ Want to work on something new. The biggest technical decisions still lie ahead. You’ll help define our infrastructure strategy, not just implement someone else’s vision.
• ✅ Thrive in uncertainty. We’re an early‑stage company. Priorities shift as we learn from customers. Requirements evolve as we understand the problem space. You find this energizing, not frustrating.
• ✅ Care about customers and their problems. You’ll work directly with customer data and build systems that power their revenue. You’ll need to understand not just how to build things, but why they matter.

This might not be the right role if you…

• 👎 Prefer staying in your lane. We’re small and fast‑moving. Engineers here work across different parts of the system and adapt as needs change.
• 👎 Want a predictable roadmap. We don’t have a year‑long backlog of perfectly scoped tickets. We figure out what to build based on customer needs and technical priorities.
• 👎 Prefer a slower pace. We’re solving real problems for customers today, which means we need to move quickly and make pragmatic tradeoffs.
• 👎 Want startup perks with big company stability. We’re early‑stage – that comes with excitement and opportunity, but not the benefits package of an established tech company.

What we offer

• The salary range for this role is £90,000 - £110,000 + share options
• Early ownership of critical infrastructure at a fast‑growing company
• Real architectural influence – your decisions will shape how we build for years
• A collaborative team that values deep technical work and continuous learning
• We support remote work within + / - 3 hours of GMT and EST, or you can work from our offices in central London or New York – whatever you prefer.

Our hiring process

1. First interview (15 mins): A 15 minute interview with an engineer to learn more about you and your experience.
2. Technical interview (60 mins): A live pair‑programming exercise with one or two of our engineers. We’ll ask you to start a new project in a language of your choice, and you’ll work with the engineers to solve some requirements and write a test suite.
3. System design interview (60 mins): Focused on how you approach system design problems, own the solutions, and apply a product mindset.
4. Final interview (30 mins): A final interview with our CEO, Riya.