Senior Software Engineer

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

Job summary

A technology company is seeking an experienced software engineer to design and build reliable systems that support millions of builds globally. You'll leverage advanced technologies like Go and Kubernetes, collaborate across teams, and mentor junior engineers, contributing significantly to the software delivery landscape. With a competitive salary range and a focus on cutting-edge AI tools, this role offers a unique opportunity to impact the industry while helping to build high-performance, scalable solutions.

Qualifications

• 5+ years of professional software development experience, including production experience writing code in Go.
• 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.

Responsibilities

• Design and build reliable, observable, zero-downtime distributed systems that serve millions of builds.
• Collaborate with cross-functional teams to shape and refine foundational capabilities.
• Mentor junior and mid-level engineers and provide technical guidance.

Skills

Go

Distributed systems

Collaboration

Software testing

Tools

Kubernetes

Datadog

Grafana

Honeycomb

Job description

About CircleCI Engineering

At CircleCI, our engineering teams are the driving force behind the platform trusted by developers worldwide to build, test, and deploy their code with confidence. We operate at a massive scale, processing over 50 million builds per month for organizations ranging from innovative startups to industry-leading enterprises. Our platform sits at a critical intersection in the software development lifecycle, where reliability, performance, and user experience directly impact the productivity of development teams around the globe.

As we continue to innovate, we're increasingly leveraging AI to transform the software delivery experience. From intelligent test selection that reduces build times, to predictive analytics that prevent pipeline failures, to AI-powered developer tools that streamline workflows, we're using machine learning and artificial intelligence to solve complex engineering challenges. We believe AI represents the next frontier in CI/CD, enabling smarter, more efficient, and more reliable software delivery pipelines.

Your work at CircleCI directly impacts how software is delivered across the industry. When you contribute to our systems—whether they're customer-facing interfaces, core platform capabilities, or developer tools—you're helping teams worldwide ship better code faster and with greater confidence. The systems you'll help build enable innovation across the entire software industry, making you an essential part of the modern development ecosystem.

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 reasonableaccommodation to participate in the job application or interview process, to performessential 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-usedDevOps tools - processing more than 3 million jobs a day - CircleCI has unique access todata on how the most effective engineering teams work, and the tools to help softwarecompanies successfully leverage the power of AI into their commercial applications.Companies like Hinge, HuggingFace, and Samsung use us to improve engineering teamproductivity, release better products, and get to market faster.

Founded in 2011 and headquartered in downtown San Francisco with a global, remoteworkforce, 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, andHarrison 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, statusas a protected veteran, status as an individual with a disability, or other applicablelegally protected characteristics. We also consider qualified applicants with criminalhistories, consistent with applicable federal, state and local law.