[Hiring] Staff ML Engineer @Buildkite

Role Description

We're hiring a Staff Engineer (ML) to join our Test Engine team. In this role, you'll define and lead the technical strategy for machine learning within Test Engine — specifically, building the models and infrastructure behind predictive test selection: using code changes to determine which tests actually need to run.

Staff Engineers at Buildkite are hands-on technical leaders. You'll influence how we design, build, and scale systems while supporting other engineers to deliver their best work. You'll be the most senior ML practitioner in the company, setting the technical direction for how we approach test selection and establishing the patterns and infrastructure that the broader ML effort builds on.

What You'll Do

• Own Technical Direction for ML in Test Engine
  • Lead and define the ML strategy for predictive test selection — from early experimentation through to models running reliably in production at scale.
  • Lead the technical investigation into how we build a generalised test selection model, and shape the approach based on what the data tells you.
  • Lead the design of the ML architecture end-to-end: feature engineering from code changes and test history, model training and evaluation, serving infrastructure, and feedback loops for continuous improvement.
  • Drive key decisions around model operationalisation — latency constraints, prediction accuracy trade-offs, and graceful degradation when confidence is low.
  • Shape how ML capabilities integrate with Test Engine's existing data infrastructure.
• Build and Scale the ML Platform
  • Build the ML platform layer so that getting a model into production is fast and repeatable.
  • Design, build, and maintain the data pipelines that feed ML workloads.
  • Train, evaluate, and deploy models, taking ownership through to monitoring and retraining in production.
  • Instrument production models with observability metrics.
  • Solve the hardest technical challenges at the intersection of code analysis and test data.
• Lead and Unblock
  • Investigate and resolve complex performance and reliability issues across the data and ML stack.
  • Share knowledge and drive engineering best practices across teams through documentation, mentorship, and pairing.
  • Support the wider engineering organisation by contributing to cross-team tooling, infrastructure, and frameworks.
  • Communicate trade-offs effectively and build alignment around technical decisions.
  • Work closely with customers to understand how test selection fits into their development workflows.

Qualifications

• Deep proficiency in Python, with strong experience building production ML systems end-to-end.
• Proven experience designing and operating ML infrastructure at scale.
• Strong experience with data processing at scale.
• Deep proficiency in SQL.
• Comfort working in cloud environments (AWS) and with containerised workloads (Docker, Kubernetes).
• Hands-on experience training, evaluating, and deploying ML models in production.
• Experience with classification, ranking, or prediction problems.
• Track record of building ML capabilities that scaled beyond a single use case.
• Experience with feature engineering from structured and semi-structured data.
• Experience instrumenting production models with observability.
• Excellent written and verbal communication skills, especially in a remote-first environment.
• A collaborative, pragmatic mindset.
• Proven ability to build alignment across teams and influence technical direction without authority.

Nice to Have

• Experience with code analysis, static analysis tools, or building features from source code structure.
• Familiarity with CI/CD systems, developer tooling, or test infrastructure.
• Experience with Ruby on Rails, React, GraphQL, or Go.
• Background in search ranking, recommendation systems, or other domains.
• Experience working with test frameworks or test execution data.

Benefits

• Competitive compensation, including salary, equity, and benefits package.
• Flexible, remote-first culture (Remote in the ANZ & PST Regions).
• Meaningful technical challenges at scale.
• Opportunities for professional growth, technical leadership, and cross-team influence.
• A collaborative, inclusive, and innovative culture where your ideas make a real impact.

Equal Opportunity Employer

At Buildkite, we value diversity and celebrate all types of skills, backgrounds, and experiences. We’re dedicated to fostering an inclusive environment and providing reasonable accommodations throughout our recruitment process.