Senior Software Engineer - Billing Automation - 12 Month FTC

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