Senior Software Engineer (Platform) in Belfast

We are looking for a collaborative engineer with a bias for action and a strong focus on delivering customer value. If you are motivated to solve complex systems problems across infrastructure, platform reliability, and backend software, and thrive in an environment where no two weeks look the same, you will find a supportive home at Cloudsmith.

About Cloudsmith

Cloudsmith is transforming how organisations handle software artifacts and secure their supply chains. As a cloud native, multi-tenant platform, we enable organisations to build software better, through best-in-class artifact management and software supply chain security. Our vision is to become the software supply chain itself, powering the future of software delivery.

We are the world's most potent artifact management platform, built by developers for developers. Our platform supports over 30 formats spanning languages, container formats, and operating systems, with enterprise-grade features, including vulnerability and security scanning, world-class policy management and enforcement, and web-scale to handle the Fortune 500. Organizations integrate Cloudsmith as critical infrastructure into their development, deployment, and distribution pipelines, trusting us to protect and accelerate, regardless of scale.

Backed by top-tier investors and on a trajectory toward IPO and beyond, we're building mission‑critical infrastructure that powers software delivery for organisations worldwide. We operate at the cutting edge of cloud‑native technology, tackling complex distributed systems challenges that directly impact millions of developers. Now is an exciting time to join us as we revolutionise how organisations deliver and secure software and help write the next chapter of our rocketship growth story.

The Role

As a Senior Software Engineer on the Core Platform team, you'll work across the systems that keep Cloudsmith fast, reliable, and scalable for our global customer base. This is a broad, high‑impact role that sits at the intersection of infrastructure and software engineering. You'll be as comfortable tuning a slow database query or diagnosing a production incident as you are designing and shipping a new platform capability. You'll need good instincts, strong technical judgement, and the ability to move with confidence in ambiguous situations.

Our Team

We are one of four engineering teams responsible for building application capabilities and the underlying platform upon which Cloudsmith is founded. We operate in a highly collaborative environment, where people with different skills come together to make things happen. We each contribute to an environment where curiosity, support, transparency, and bias for action reign. We have a modern CI/CD approach, deploying several times per day, and we support a global set of customers who are engineers like us.

The Platform team is cross‑cutting by nature. You won't own a single service in isolation. Instead, you'll work across layers of the stack, from AWS infrastructure through to backend application code, tackling problems that don't always have a well‑worn path. One week might involve investigating a performance regression affecting an enterprise customer; the next, designing changes to how our platform handles authentication or billing at scale.

This is a rare opportunity to work on systems that matter — mission‑critical infrastructure used by some of the world's most demanding engineering organisations — alongside a small, senior team that takes pride in doing things well.

Our Technology Stack

We are cloud‑native, born in AWS, and embrace their services across our platform. Our technology stack includes Python, Django, React, NextJS, ECS, Postgres, Clickhouse, Kinesis, Cloudfront, Flink, Elastic Search, Lambda, AmazonMQ & Terraform. Tooling includes VS Code, Slack, Linear, Datadog, Notion, CircleCI & Spacelift.

Key Responsibilities

• Build: Design, build, and ship new features and optimisations for our platform infrastructure.
• Resilience: Help keep our systems fast, reliable, and running smoothly at a global scale.
• Collaborate: Work closely with teammates from product, design, and customer success to solve complex problems together.
• Quality: Prioritise quality and security through rigorous testing, monitoring, and sustainable engineering habits.
• Mentor: Share your knowledge through code reviews, documentation, and mentoring others to foster a growth‑oriented environment.

Required Experience, Qualities & Skills

We realise that not everyone will have every experience and expertise in every possible thing. Still, if you have many of the following, we might be a great place to progress your career.

• Experience: 5+ years (or equivalent) of professional experience building, testing, and maintaining complex distributed systems in production.
• Technical Proficiency: Proficiency with programming languages such as Python (Django), Golang, Rust, Java, or similar.
• Infrastructure: Familiarity with cloud‑based infrastructure and related services (AWS, CloudFront, Lambda, ECS, Postgres, S3, Kinesis, Terraform), container runtimes, event‑driven architectures (high volume data pipelines), and continuous integration.
• Iterative Delivery: You understand the importance of shipping early and often and delivering value iteratively.
• Communication: An enthusiastic and effective communicator who can bridge the gap between technical and non‑technical stakeholders.
• Mindset: Deeply passionate about your craft, eager to learn, and comfortable admitting what you don't yet know.

Benefits, Location & Work Environment

Note: You must be based in Ireland or the United Kingdom and have the right to work independently without requiring sponsorship.

• A position based in Ireland or the United Kingdom.
• A competitive compensation package, including equity.
• With comprehensive health, dental, and vision insurance.
• Plus, generous annual leave and flexible working policies to suit your lifestyle.
• Including a professional development budget for conferences and training.
• In a dynamic, innovative, trust‑centric, and supportive work environment.
• With the opportunity to shape a fast‑growing Series B startup (and beyond).
• Regular (monthly‑ish) travel may be required for company gatherings and engineering days.

Health and Wellness

Regardless of your location, we deeply care about the health and wellness of our staff and their families; a sustainable pace is important to us. In addition to generous annual leave (PTO), we offer health and well‑being benefits along with flexible family‑friendly working policies.

Personal Growth

You will have an enormous opportunity to learn new skills alongside your colleagues, and your continued professional development is essential to us because it's important to you. We will support you with budgets for equipment, training, books, conferences, travel, and certifications. The more powerful you become, the better for all of us.

Facilities

Cloudsmith is headquartered in Belfast, Northern Ireland, with fully‑equipped office space that’s open 24x7. We use our H.Q. regularly for activities like working sessions, team planning, meets and greets, and sometimes other group activities (like games!). We also hold all‑hands off‑sites in Belfast three times a year, featuring guest speakers and team activities. Many Cloudsmithers work remotely, so we rely on our online collaboration tools; Slack, Google Docs, Linear, and other popular collaboration tools are how we work.

About Equal Opportunity

Cloudsmith is an equal‑opportunity employer proud to nurture a diverse workplace that welcomes applications from individuals of all races, genders, and ethnic groups. We do not discriminate on age, religion, sexual orientation, citizenship status, military service, or health conditions. We will not tolerate discrimination of any kind within our workforce.

The Final Word

We’re looking for someone who has a passion for their craft, a collaborative attitude, and a desire to build a product customers love. We are critical infrastructure built by developers for developers, and we are building the world’s software supply chain platform and ecosystem. We want to hear from you if you are excited to build a high performing platform that powers software delivery at a global scale - balancing thoughtful design with real‑world constraints - to leave a lasting impact on the software industry from today until IPO and beyond.