Senior Software Engineer - Billing Automation - 12 Month FTC

Title: Senior Software Engineer - Billing Automation - 12 Month FTC Location: Poland

What We're All About

Any company can tell you about how they are a multi award winning, market leading business — and yes, we are both of those things in the world of IoT connectivity. But we're more than that. Our mission is to make IoT management a breeze for any device, any where.

With over 10 million IoT subscriptions active in 165 countries and direct partnerships with 50 mobile networks, we connect customers to more than 750 networks worldwide, delivering unmatched value across the IoT connectivity chain.

Innovation is in our DNA, and we have an insatiable hunger to 'wow'. While we may not always get it right, our drive to collaborate, innovate, and achieve top-notch customer satisfaction never wavers.

The Role — Interstellar Squad

The Interstellar Squad owns a core part of our commercial platform: the billing run — a mission-critical, high-volume pipeline that turns large-scale usage data into timely, accurate invoices for customers worldwide. It's a technically rich and genuinely complex domain: distributed data processing, event-driven workflows, financial correctness, and operational reliability at scale.

We're looking for a Senior Product Engineer — a hands-on full-stack engineer who is predominantly backend-focused, with deep TypeScript and NestJS experience, but equally able to build React applications. You'll be at home with event-driven processing (Kafka or RabbitMQ) and confident working deep in PostgreSQL. You'll help shape key elements of our billing solution, taking ownership of meaningful pieces of the platform from understanding the business problem through to running your code in production.

The squad is gradually modernising a mature platform into a set of focused, TypeScript-based domain services, using a strangler-fig approach to extract capabilities incrementally while keeping the existing system safe and our customers unaffected. You'll be one of the engineers designing and building those new services, working within the technical direction set by the Engineering Lead.

You'll report to an Engineering Manager and work day to day with the squad's Engineering Lead, Product Manager, Delivery Manager and other engineers, as well as stakeholders from the wider business who depend on billing being right.

This role is based in Poland to work alongside the rest of the squad.

Key Responsibilities

• Design, build and maintain TypeScript / NestJS domain services — for our billing platform that are correct, well tested and easy to operate
• Build React applications — clean, well-tested front ends on top of the services you build, so that users and colleagues can work with billing data and processes effectively
• Shape elements of our billing solution — work with Product and domain experts to understand complex billing rules and model them clearly in code, data and service boundaries
• Build and evolve event-driven, asynchronous workflows — on Kafka or RabbitMQ, with careful attention to idempotency, retries, ordering, error handling and recoverability
• Design and optimise PostgreSQL schemas and queries — for data-intensive billing processes — data modelling, indexing, query tuning and diagnosing performance issues on large data sets
• Contribute to the modernisation of the platform — under the technical direction set by the Engineering Lead — helping to define seams, extract capabilities safely and keep billing correct through each incremental cut-over
• Own your work end to end — from refinement and technical design through implementation, thorough automated testing (unit, integration and end-to-end where it matters), release and production support — working self-sufficiently and knowing when to pull others in
• Contribute to technical decisions — propose approaches, articulate trade-offs and document them, so the squad can make well-informed choices
• Uphold engineering standards — for code quality, type safety, testing, observability and operational readiness across the services you work on
• Help keep our services healthy in production — contribute to SLIs/SLOs and dashboards (Grafana), take part in investigating and resolving incidents, and follow through on improvements
• Use and improve our CI/CD pipelines (GitLab) to keep releases small, frequent and safe
• Collaborate closely with Product and business stakeholders — to clarify requirements in a complex domain, explain technical trade-offs in plain language, and flag risks early
• Give thoughtful code reviews — and share knowledge, supporting less experienced engineers in the squad
• Use AI-assisted engineering tools responsibly (IDE agents, CLI tooling, reviews), staying accountable for the correctness of what ships

Key Experience & Skills

Required

• Solid commercial experience as a backend-focused or full-stack engineer (typically 5+ years), delivering and running business-critical systems in production
• Deep, production-proven expertise in TypeScript and NestJS — strongly typed design, dependency injection, modular / clean architecture and good testing practice
• Commercial experience building React applications in TypeScript — comfortable delivering features across the stack, from the API through to the UI
• Hands-on experience with event-driven / asynchronous processing — using Kafka or RabbitMQ (or a comparable message broker)
• Strong command of PostgreSQL — data modelling, query design, indexing and performance tuning on large volumes of data
• Proven experience working in a complex business domain (e.g. billing, finance, payments, telecoms, insurance) — able to dig into domain rules, ask the right questions and model them well in code
• Experience building data-intensive, business-critical services — where correctness, idempotency and recoverability matter
• Self-sufficiency — able to take loosely defined problems, break them down and drive them to completion with minimal supervision
• Strong communication and stakeholder skills — can explain trade-offs clearly and honestly to engineers, Product and non-technical stakeholders

Preferred

• Familiarity with AWS-based platforms (e.g. ECS, S3, Parameter Store, SES), including Infrastructure as Code with Terraform
• Experience working with CI/CD pipelines — ideally GitLab, and automated testing within them
• Practical experience with observability — metrics, tracing, logs and SLO-driven operation; Grafana or similar
• Experience contributing to the modernisation or decomposition of a monolith — e.g. strangler-fig, anti-corruption layers, contract design, incremental cut-overs
• Background in billing, financial, or metering/rating domains
• Familiarity with domain-driven design concepts (bounded contexts, aggregates, domain events)
• Experience with distributed/sharded PostgreSQL setups (e.g. Citus)
• Sensible, hands-on use of AI-assisted development tools (e.g. Cursor, Claude Code, GitHub Copilot) with a thoughtful view on where they help and where they don't
• Any exposure to PHP — helpful for understanding our legacy platform, but not essential

What Will Make You Shine at Wireless Logic

• Takes ownership — treats the billing platform as their own and cares about outcomes, not just tickets
• Creates clarity — turns ambiguous domain problems into simple, well-structured solutions
• Cares about correctness — thinks about edge cases, failure modes and data integrity before they become incidents
• Modernises pragmatically — builds new services with care while respecting the existing system that keeps the lights on
• Communicates early and openly — shares progress, risks and trade-offs with the team and stakeholders
• Manages technical debt with intent — makes informed, defensible calls about when to refactor
• Partners with Product — understands the business outcome behind the work and shapes the solution accordingly
• Lifts the team — shares knowledge through reviews, pairing and documentation
• Keeps learning — including thoughtful adoption of new tooling and AI-assisted workflows

Why Come Work with Us?

• The chance to join a creative, entrepreneurial company where bold ideas are celebrated
• Full training, ongoing support, and the tools to help you thrive and grow in your role
• A company with heart — we genuinely care about our people and make sure everyone feels valued, respected, and part of the team

Overview of Interview Process

• Recruiter Call - Meet the HR team
• Online Technical Task
• Behavioural Interview — Meet your hiring manager & delivery manager
• Technical Interview — Meet the Engineering Lead and a peer engineer (expect a discussion on TypeScript/NestJS, event-driven design and PostgreSQL, plus some front-end work in React)
• Technical Leadership Interview - Meet the Leadership Team

How We Work

We've adopted a remote/hybrid working approach to give flexibility on where and how we work. This role is based in Poland to support squad collocation; you'll find out more about what this means for the role during the recruitment process.