Senior Software Engineer - k6 Core

The Opportunity:

At k6, we build reliability and performance testing tools for developers and QA engineers.

Grafana k6 is an open-source project focused on making performance testing practical, approachable, and useful in real-world engineering workflows. We care deeply about developer experience, correctness, and scalability. k6 is part of the Grafana ecosystem and is used by engineers to test and understand systems under real load.

What You’ll Be Doing:

You will join a team of engineers responsible for building and maintaining k6, a performance testing tool written in Go. The team also maintains the open-source project, which means working directly on the product, the codebase, and with the community using it.

In this role, you will work on features and improvements across the k6 codebase, from initial idea through implementation and delivery. Much of the work involves problems that are not fully specified up front and require understanding the context, evaluating trade-offs, and choosing a reasonable technical approach.

You will work with a high degree of independence while collaborating closely with other engineers on design, implementation, and code reviews. You are expected to deliver production-quality code, maintain existing functionality, and help keep the system reliable and maintainable over time.

Some work may involve the k6 cloud offering, which builds on top of k6 to run distributed tests across data centers worldwide. This includes Go services that support distributed execution and require careful attention to performance, correctness, and failure modes.

Because the team is small, your work will have a direct and visible impact on the product and its users. You will work alongside experienced engineers in an environment that values clarity, pragmatism, and sound engineering judgment.

We invest heavily in developer productivity. You can use modern AI coding assistants as part of your daily workflow (your choice of tools, within security guidelines), backed by a company-funded usage budget so you can iterate quickly without unnecessary friction. We encourage pragmatic AI-assisted development: faster prototyping, test generation, refactors, documentation, and incident follow-ups—always with strong code review and quality standards. You'll also have access to the latest frontier models from OpenAI, Anthropic, and Google.

What Makes You a Great Fit: 

We start with problems, not prescriptions. Engineers are expected to understand the constraints, propose a pragmatic design, and carry the work through to delivery. We move deliberately and release on a regular cadence of roughly every six weeks. Between releases, we focus on small, safe, incremental changes.

Work is asynchronous by default, with decisions captured in pull requests and short design notes. Meetings are used for alignment rather than status updates. Code reviews focus on correctness, long-term maintainability, and user impact. When trade-offs are required, we aim to make them explicit and reversible. The team owns the product end to end, including architecture, releases, user-facing behavior, and the health of the open-source project.

We’re looking for an experienced engineer with strong programming skills and a track record of working on non-trivial systems.

You should have:

• Strong experience building production software in Go, or another language with good support for concurrency and parallelism
• Experience working on larger or long-lived codebases
• The ability to work independently on scoped problems and deliver them to completion
• Clear technical communication skills, especially in code reviews and design discussions
• A good understanding of internet protocols such as HTTP, gRPC, and WebSockets, with some familiarity with lower-level networking concepts
• Experience with modern development practices, including testing, code review, and iterative development

Bonus Points For:

You do not need experience with everything listed below. These are areas where familiarity is useful for the role, and the more you bring, the easier the ramp-up will be:

• Contributing to or maintaining open-source projects
• Prior experience using k6 in production, or contributing to the k6 project or ecosystem
• Performance, reliability, or network testing and optimization
• Distributed systems or cloud-based services
• JavaScript and/or TypeScript
• Backend systems for web or mobile applications
• Tools and platforms such as Docker, AWS, microservices architectures, and observability tools like Grafana or APM systems

Compensation & Rewards:

In Spain, the Base compensation range for this role is EUR 82,988  -  EUR 99,586.  Actual compensation may vary based on level, experience, and skillset as assessed in the interview process. All of our roles include Restricted Stock Units (RSUs), giving every team member ownership in Grafana Labs' success. We believe in shared outcomes—RSUs help us stay aligned and invested as we scale globally.