Senior Software Engineer

CircleCI; City Of London; On-site; GBP 90,000 - 113,000; Full time

Job summary

A leading CI/CD platform provider in the UK seeks a skilled Software Engineer to design and build reliable systems that serve millions of builds. Your role will involve mentoring junior engineers, collaborating with teams, and solving complex problems. Ideal candidates have 5+ years of experience in software development, deep knowledge of Go, and experience with distributed systems. This position offers a competitive salary and the chance to work in a fast-paced, innovative environment.

Qualifications

• 5+ years of professional software development experience.
• Deep proficiency in Go programming.
• Experience with testing strategies and distributed systems.

Responsibilities

• Design and build reliable distributed systems.
• Collaborate with teams to refine capabilities.
• Mentor junior engineers and contribute to team culture.

Skills

Proficiency in Go

Testing skills

Distributed systems experience

Collaboration

Tools

Kubernetes

Honeycomb

Datadog

Grafana

Rollbar

Job description

About CircleCI Engineering

At CircleCI, our engineering teams power the platform trusted by developers worldwide to build, test, and deploy with confidence. We operate at massive scale—processing over 50 million builds per month for companies ranging from fast-moving startups to global enterprises—and sit at a critical point in the software delivery lifecycle where reliability, performance, and user experience directly shape developer productivity.

Engineering here is about momentum and impact. We move quickly to explore ideas, validate what works, and double down on solutions that create real value for users. Our engineers are builders at heart: comfortable navigating ambiguity, making pragmatic tradeoffs, and approaching technical decisions through the lens of customer outcomes. Speed and experimentation matter, but so does the discipline to evolve prototypes into durable, production-ready systems.

Looking ahead, we’re weaving AI into the fabric of CI/CD—from intelligent test selection that reduces build times to predictive insights that prevent pipeline failures. By combining scale, speed, and intelligent tooling, the systems you build at CircleCI don’t just power our platform—they shape how software is delivered across the industry, helping teams everywhere ship better code, faster, with greater confidence.

Team-Agnostic Placement

We hire team-agnostically at CircleCI, meaning we don’t recruit for a single team from the start. Instead, we get to know each candidate through the interview process and then place them on the team where their strengths, interests, and experience will make the greatest impact. This approach allows us to be thoughtful about matching engineers with the right challenges, and it gives new hires a stronger foundation for long-term success and growth. It’s part of our commitment to building balanced, high-performing teams that are set up to thrive.

By carefully matching your skills to the right team, we ensure you can make the most meaningful impact on systems that are critical to the success of development teams worldwide.

What You’ll Do

• Design and build reliable, observable, zero-downtime distributed systems that serve millions of builds across thousands of customers.
• Collaborate with cross-functional teams to shape and refine foundational capabilities.
• Own your work from concept to deployment and beyond—digging into production issues using tools like Honeycomb, Datadog, Grafana, and Rollbar to ensure system health.
• Write clear, maintainable, and well-documented Go code, with observability and long-term maintainability built in.
• Participate in architectural decisions and technical strategy development.
• Lead complex projects and initiatives from inception to completion.
• Mentor junior and mid-level engineers and provide technical guidance to the team.
• Contribute to a culture of continuous improvement, helping your team and our customers succeed.
• Continue your professional growth through increased technical scope, leadership opportunities, and strategic impact, supported by mentorship from experienced leaders and exposure to complex engineering challenges across the organization.

What You’ll Bring

• 5+ years of professional software development experience, including production experience writing code in Go. Your broader background may span backend, frontend, AI/ML, or full-stack systems.
• Deep proficiency in Go and experience delivering production-quality software at scale.
• Strong testing skills with experience writing comprehensive unit, integration, and end-to-end tests.
• Proven experience building and maintaining distributed systems in real-world environments.
• Familiarity with Kubernetes and modern cloud infrastructure.
• A production-first mindset, comfortable monitoring, supporting, and debugging live systems.
• A pragmatic approach to engineering, solving problems efficiently while balancing complexity and maintainability.
• A collaborative spirit and a desire to grow, mentor, and lead alongside others.

Bonus Skills (Nice to Have)

• Experience with AI/ML technologies or integrating LLMs into applications.
• Interest in using AI to enhance developer tooling or automate development workflows.
• Knowledge of using machine learning for test selection, build optimization, or predictive CI/CD insights.
• Background in frontend development with frameworks like React and TypeScript.
• Familiarity with observability and performance optimization practices.

United Kingdom Base Pay Range £90,000 — £113,000 GBP

We will ensure that individuals with disabilities are provided reasonable accommodation to participate in the job application or interview process, to perform essential job functions, and to receive other benefits and privileges of employment. Please contact us to request accommodation.

About CircleCI

CircleCI is the world’s largest continuous integration/continuous delivery (CI/CD) platform, and the hub where code moves from idea to delivery. As one of the most-used DevOps tools - processing more than 3 million jobs a day - CircleCI has unique access to data on how the most effective engineering teams work, and the tools to help software companies successfully leverage the power of AI into their commercial applications. Companies like Hinge, HuggingFace, and Samsung use us to improve engineering team productivity, release better products, and get to market faster.

Founded in 2011 and headquartered in downtown San Francisco with a global, remote workforce, CircleCI is venture-backed by Base10, Greenspring Associates, Eleven Prime, IVP, Sapphire Ventures, Top Tier Capital Partners, Baseline Ventures, Threshold Ventures, Scale Venture Partners, Owl Rock Capital, Next Equity Partners, Heavybit, and Harrison Metal Capital.

CircleCI is an Equal Opportunity and Affirmative Action employer. We do not discriminate based upon race, religion, color, national origin, sexual orientation, gender, gender identity, gender expression, transgender status, sexual stereotypes, age, status as a protected veteran, status as an individual with a disability, or other applicable legally protected characteristics. We also consider qualified applicants with criminal histories, consistent with applicable federal, state and local law.