About Buildkite

Buildkite's CI platform is trusted by the world's leading engineering teams, shipping software to over 1,000,000,000 daily users.

Job Overview

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.

🔧 About the Team

The Test Engine team helps engineering teams ship faster by giving them visibility and control over their test suites. Today, that means real-time flaky test detection and management, intelligent test splitting across parallel jobs, and performance analytics and tracing — all working across any CI/CD platform, not just Buildkite Pipelines.

Test Engine already ingests billions of test runs. We have deep visibility into test suites, codebases, and the relationships between them. The next step is using that data to answer a fundamental question: for a given code change, which tests are most likely to fail?

We believe the industry is moving away from running full test suites on every change. The teams that can shift their outer testing loop into a fast, precise inner loop — running only the tests that matter — will ship value to their customers dramatically faster. For many of our customers, that speed is existential. Switching costs are low, competition is fierce, and the teams with faster feedback loops win.

This is where ML comes in. If we can model the relationship between code changes and test failures, we can give engineering teams a fundamentally faster development cycle. We're not trying to optimise individual tests — we're trying to build a generalised solution to test selection that works across codebases, frameworks, and languages.

🚀 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 (test selection has to be fast enough to sit in the critical path), prediction accuracy trade-offs, and graceful degradation when confidence is low
• Shape how ML capabilities integrate with Test Engine's existing data infrastructure — billions of ingested test runs, test-to-code mapping, and the intelligent splitting engine

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 — connecting code change signals with test execution history at scale
• Train, evaluate, and deploy models, taking ownership through to monitoring and retraining in production
• Instrument production models with observability metrics: prediction accuracy, latency, coverage, false negative rates, and drift detection
• Solve the hardest technical challenges at the intersection of code analysis and test data — feature extraction from diffs, generalisation across languages and frameworks, and handling the cold-start problem for new tests and repositories

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, and ensure the product delivers real impact

🎨 Skills & Experience We Value

Technical Expertise

• Deep proficiency in Python, with strong experience building production ML systems end-to-end
• Proven experience designing and operating ML infrastructure at scale — model registries, feature stores, serving layers, experiment tracking, or similar
• Strong experience with data processing at scale — whether batch or streaming frameworks (Spark, Flink, or similar)
• Deep proficiency in SQL
• Comfort working in cloud environments (AWS) and with containerised workloads (Docker, Kubernetes)
• In short, we'd expect equal comfort and high level capability in the end to end process from designing and building models through to deploying them.

ML & Domain Experience

• Hands-on experience training, evaluating, and deploying ML models in production — you're a practitioner, not only an infrastructure builder
• Experience with classification, ranking, or prediction problems where the signal-to-noise ratio is challenging — test selection shares characteristics with anomaly detection, change-point detection, and predictive filtering
• Track record of building ML capabilities that scaled beyond a single use case — not just one-off models but repeatable, generalised approaches
• Experience with feature engineering from structured and semi-structured data (code diffs, execution logs, dependency graphs, or similar)
• Experience instrumenting production models with observability: accuracy, latency, coverage, drift

Collaboration and Communication

• Excellent written and verbal communication skills, especially in a remote-first environment
• Ability to distil complex technical concepts into clear explanations for diverse audiences
• A collaborative, pragmatic mindset — balancing technical quality with business context
• Comfortable mentoring engineers and leading technical discussions across teams
• 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 where you're predicting relevance from sparse signals
• Experience working with test frameworks or test execution data

✨ Why Join Buildkite

At Buildkite, we value kindness, autonomy, and collaboration. You'll be joining a remote-first company where your work directly helps some of the world's best engineering teams build and ship software faster and more safely.

• 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

About Buildkite

At Buildkite, our mission is to unblock every developer on the planet. We’ve rethought how software delivery should work and have built a platform that is fast, reliable, secure, and able to scale to the needs of the most demanding high-growth tech companies globally including Uber, Airbnb, Shopify, Canva, PagerDuty, Lyft, and Pinterest.

Our engineering teams work across AU/NZ and US Pacific time zones — a deliberate choice that lets us move fast with real-time collaboration. At the moment, we are prioritising engineers who are based in these regions.

Job Overview

In this role, you’ll help design, build, and scale tools that empower some of the world’s best software engineering teams. You’ll collaborate closely with engineers, designers, and product managers to deliver impactful features and improvements while working on challenges at the intersection of developer experience, scalability, and performance.

This is a highly collaborative, hands-on role where you’ll contribute to product development, influence architectural decisions, and help shape the future of Buildkite’s platform.

🚀 What You’ll Do

• Collaborate with the engineering team to shape upcoming feature or fix
• Work deeply in our Ruby on Rails monolith, including our PostgreSQL databases
• Investigate and resolve issues in our production systems — following a problem from symptom to root cause
• Provide or respond to feedback on GitHub pull requests
• Help customers unblock themselves by diagnosing product behaviour or pipeline issues
• Iterate on schema and data changes, and ensure migrations and deploys remain safe and smooth (we ship code on Fridays!)
• Contribute to architectural discussions and help steer the technical direction of the product

🎨What You Bring

• 5+ years of experience in engineering
• Have deep experience designing, developing, and maintaining complex Ruby on Rails applications in production
• Comfortable working with performance at scale from N+1 queries to indexing strategies to diagnosing slow paths
• Experience using observability tools like Datadog, Honeycomb, etc.
• Care about code quality and know how to balance perfect with practical
• Enjoy solving hard problems with minimal supervision. You can zoom out to see the big picture and zoom in to debug a specific query, API call, or race condition
• Comfortable wearing many hats: helping a customer one moment, pitching an idea to the team the next, digging into the database, or refining product requirements
• Understand good development practices: writing clear commits, thoughtful pull requests, and reliable tests with tools like RSpec

Key Technical Stacks & Components:

• Ruby on Rails
• PostgreSQL
• GraphQL
• React
• Amazon ECS 
• RDS Performance Insights
• Terraform
• Redis
• Golang
• Kafka

✨ Why Join Buildkite

At Buildkite, we value kindness, autonomy, and collaboration. You’ll be part of a remote-first company where your work can make a meaningful impact – empowering engineers worldwide to build and deliver better software faster.

• Competitive compensation and benefits package
• Flexible, remote-first culture 
• Opportunities for professional growth, leadership, and technical ownership
• Work alongside talented, passionate engineers building world-class developer tools
• A collaborative, inclusive, and innovative culture where your ideas make a real impact

At Buildkite, our mission is to unblock every developer on the planet. We've rethought how software delivery should work and have built a platform that is fast, reliable, secure, and able to scale to the needs of the most demanding high-growth tech companies globally, including Airbnb, Shopify, Canva, PagerDuty, Lyft, and Pinterest.

Job Overview

We're hiring a Staff Engineer to join our Compute and Agents team. In this role, you'll help set technical direction for the team, lead architectural decisions across complex systems, and drive the work that has the highest impact on Buildkite's infrastructure and developer experience. You'll shape how we build and scale our agent infrastructure, hosted compute, and MCP service — balancing reliability, performance, and security at scale.

This is a hands-on role. You'll write code, own the hardest problems, and raise the engineering bar across the team through standards, mentoring, and the quality of your own work.

🔧 About the Team

The Compute and Agents team builds, maintains, and iterates on the infrastructure that keeps Buildkite humming — from our open-source agent trusted by engineers around the world, to our hosted agents and MCP service. It's a team that sits at an intersection of deeply technical infrastructure work and the fast-moving world of AI agents, with our own agent in the middle.

There's real ownership here. You'll work on problems that matter to developers everywhere, shipping work you can point to and be proud of — alongside a sharp, kind team that loves digging into hard problems together.

🚀 What You'll Do

• Help guide the technical direction for the Compute and Agents team, shaping architecture and system design decisions
• Lead the hardest cross-system integrations and drive solutions to complex infrastructure challenges
• Design and evolve systems, patterns, and standards that improve reliability, performance, and operability across teams
• Write code, review code, and pair with engineers — leading by example on quality and craft
• Build alignment across teams and stakeholders on technical decisions, balancing speed, quality, and impact
• Collaborate with engineers, designers, and product managers to shape solutions that solve customer problems
• Mentor and upskill engineers within the team, raising capability and setting shared standards
• Lead cross-team reliability, performance, and cost initiatives; set operational readiness expectations for major changes
• Participate in customer research and discovery sessions to inform product and architectural decisions

🎨 Skills & Experience We Value

Core Skills:

• Strong communication skills, with empathy and kindness in both written and verbal collaboration
• Proven experience leading technical direction within or across engineering teams
• Repeated ownership of large or complex production systems, with clear evidence of impact beyond a single team
• Ability to make strategic trade-offs, articulate decisions clearly, and build alignment in ambiguous situations
• Strong judgment about where to invest versus where to simplify
• Comfortable working directly with customers and incorporating feedback into product development
• Familiarity with CI/CD systems, developer tooling, and DevOps concepts

Technical Stack:

• Go — our primary language, used across our agents and infrastructure. Strong experience or a genuine eagerness to go deep is a must.
• Kubernetes & AWS — we run cloud-native infrastructure at scale. Experience with container orchestration and distributed systems is a big plus.
• Terraform — we manage our infrastructure as code with Terraform. Familiarity with IaC principles and writing reusable, maintainable Terraform is valued.
• Ruby on Rails — the backbone of the Buildkite platform. The majority of our product is built here, so comfort with Rails or a willingness to pick it up matters.
• React & GraphQL — our frontend and API layer, used across the platform alongside Rails.
• PostgreSQL — experience with query optimisation, schema design, or managing relational databases under load is a plus.

🗓 A Typical Day Might Include

• Leading an architecture discussion for a new capability or system change
• Reviewing pull requests with detailed, constructive feedback
• Pairing with an engineer on a complex infrastructure problem
• Investigating performance bottlenecks or scaling challenges
• Driving alignment across teams on a cross-cutting technical decision
• Joining a customer discovery session to understand how teams use agents at scale
• Writing code on the hardest or most ambiguous parts of the work

✨ Why Join Buildkite

At Buildkite, we value kindness, autonomy, and collaboration. You'll be part of a remote-first company where your work can make a meaningful impact — empowering engineers worldwide to build and deliver better software faster.

• Competitive compensation and benefits package
• Flexible, remote-first culture
• Opportunities for professional growth, leadership, and technical ownership
• Work alongside talented, passionate engineers building world-class developer tools
• A collaborative, inclusive, and innovative culture where your ideas make a real impact

Buildkite’s CI platform is trusted by the world’s leading engineering teams, shipping software to over 1,000,000,000 daily users.

Job Overview

We're looking for a Staff Engineer to join our Releases team. In this role, you'll help solve some of the most challenging technical problems we face as we continue to scale Buildkite's platform. You'll drive architectural decisions, lead technical strategy, and work closely with engineers, designers, and product managers to deliver impactful improvements.

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.

🔧 About the Team

The Releases team is building Buildkite's release control plane — a foundational layer that gives platform teams one trusted, auditable view of what shipped, where, and whether it met governance requirements.

Our initial focus is designing a canonical release model (service, environment, commit, artefact, actor, status), reliable ingestion from Pipelines and GitHub Deployments, and an immutable evidence trail that powers policy gates and DORA metrics.

Beyond that foundation, the same platform becomes a progressive delivery product: staged rollouts, canary analysis, blue/green deploys, health-based promotion, and automatic rollback. In short, we're moving from observing and governing releases to orchestrating and optimising them — integrating cleanly with existing CD systems rather than forcing a full replacement.

🚀 What You’ll Do

Own Technical Direction for the Releases Platform

• Design the release architecture and core data model, including the canonical release entity and its relationships across services, environments, artefacts, and actors

• Lead key technical decisions around security, reliability, and scale — particularly for the immutable evidence trail and policy gate infrastructure

• Drive the hardest cross-system integrations, including ingestion from Pipelines and GitHub Deployments

• Ensure the platform is extensible enough to support progressive delivery capabilities (canary analysis, staged rollouts, health-based promotion, automatic rollback) without requiring customers to replace existing CD tooling

Build and Improve the Releases Platform

• Design, build, and scale tools and systems relied on by some of the best engineering teams in the world

• Solve complex technical challenges around performance, reliability, and scalability

• Work closely with customers and stakeholders to deeply understand their release and governance challenges, and deliver practical, high-impact solutions

• Drive improvements to developer experience through better tooling, automation, and processes

Lead and Unblock

• Investigate and resolve complex performance and reliability issues across the stack

• Explore systems at every layer — from infrastructure patterns to backend services and data stores

• 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

🎨 Skills & Experience We Value

Technical Expertise

• Proven experience working in production environments at scale, ideally using Go, Ruby on Rails, or similar languages
• Experience designing event-driven or audit-log systems — immutable records, event sourcing, or append-only data models are a strong plus
• Deep understanding of cloud infrastructure and deploying complex, containerised applications (AWS experience preferred)
• Familiarity with PostgreSQL or similar relational databases, including reasoning about performance and replication
• Comfortable solving challenges in distributed systems, observability, and infrastructure reliability

Domain Experience

• Familiarity with CD systems, deployment pipelines, or release orchestration platforms (e.g. Spinnaker, Argo Rollouts, Flux, or similar)
• Understanding of progressive delivery patterns: canary deployments, blue/green, feature flags, health-based promotion, and rollback strategies
• Experience with DORA metrics, release governance, or compliance/audit requirements in regulated or large-scale engineering environments
• Background in integrating with source control and CI/CD platforms (GitHub, GitLab, Buildkite, etc.)

Collaboration and Communication

• Excellent written and verbal communication skills, especially in a remote-first environment
• Ability to distil complex technical concepts into clear explanations for diverse audiences
• A collaborative, pragmatic mindset — balancing technical quality with business context
• Comfortable mentoring engineers and leading technical discussions across teams

Additional Experience

• Kubernetes, Terraform, or other infrastructure-as-code tools
• Familiarity with Kafka, Flink, or other streaming/event-driven systems
• Background in SRE, systems programming, or Linux/Unix internals
• Understanding of secure system design and cloud security best practices

✨ Why Join Buildkite

At Buildkite, we value kindness, autonomy, and collaboration. You’ll be joining a remote-first company where your work directly helps some of the world’s best engineering teams build and ship software faster and more safely.

• 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. If you need any accommodations or support during the application or interview process, please reach out to us at accommodations@buildkite.com.