Software Engineer II - QuantumBlack Labs

Driving lasting impact and building long-term capabilities with our clients is not easy work. You are the kind of person who thrives in a high performance/high reward culture - doing hard things, picking yourself up when you stumble, and having the resilience to try another way forward. In return for your drive, determination, and curiosity, we will provide the resources, mentorship, and opportunities you need to become a stronger leader faster than you ever thought possible. Your colleagues—at all levels—will invest deeply in your development, just as much as they invest in delivering exceptional results for clients.

Every day, you will receive apprenticeship, coaching, and exposure that will accelerate your growth in ways you won’t find anywhere else. When you join us, you will have:

• Continuous learning: Our learning and apprenticeship culture, backed by structured programs, is all about helping you grow while creating an environment where feedback is clear, actionable, and focused on your development.
• A voice that matters: From day one, we value your ideas and contributions. You’ll make a tangible impact by offering innovative ideas and practical solutions, all while upholding our unwavering commitment to ethics and integrity.
• Global community: With colleagues across 65+ countries and over 100 different nationalities, our firm’s diversity fuels creativity and helps us come up with the best solutions for our clients.
• World-class benefits: On top of a competitive salary, we provide a comprehensive benefits package to enable holistic well-being for you and your family.

You will be part of QuantumBlack Labs and work in a team of software engineers, product managers, data scientists, data engineers and designers to create innovative products and new technologies that accelerate and scale our work in artificial intelligence and machine learning. We hire engineers into multiple product teams (e.g. agentic AI systems, digital twins, advanced analytics platforms). Team placement will depend on your skills and interests.

Our teams in QuantumBlack Labs are responsible for designing products that explain complex data landscapes and insights to our users, building frameworks and libraries that enable Data Scientists, Data Engineers, and Machine Learning Engineers to work effectively on large-scale, complex projects—including open-sourcing some of these frameworks, such as Kedro and ARK—and developing innovative, industry-specific AI/ML solutions that embed our distinctive technical approach and business knowledge for enterprise clients.

As a Software Engineer II, you will collaborate with interdisciplinary teams to design and deliver innovative solutions. You’ll continuously enhance your skills, address user needs, and contribute to building impactful, high-quality products that drive real-world outcomes. In this role, you will take initiative in your learning and development. You will actively seek opportunities to grow by participating in training, conferences, and hands-on projects.

Your work will have a real-world impact by driving innovation and delivering scalable solutions. By collaborating with diverse teams, you will contribute to McKinsey’s shift toward asset-based consulting, helping to create high-value tools that address critical client needs and shape industry-leading outcomes.

You will join our London or Madrid office and collaborate within cross-functional teams to create and develop innovative tools and products by managing workstreams, engaging in discussions, and crafting technical solutions tailored to user needs. Your responsibilities will include working collaboratively in Agile teams through code reviews, pair programming, and iterative delivery, where you will deliver well-structured, production-quality code, own small–medium features end-to-end, participate in design discussions with senior engineers, write tests, document code, maintain high reliability, and engage in code reviews while contributing to team best practices.

This role offers an exceptional opportunity to grow as a technologist and leader. With McKinsey’s global network, leadership development resources, and exposure to cutting-edge challenges, you will expand your expertise, collaborate with inspiring teams, and play a key role in advancing technology innovation.

Your Qualifications and Skills

• Degree in computer science or related field, or equivalent practical experience
• 2-5+ years of relevant experience
• Experience building production-grade applications in at least one part of the stack (backend, frontend, infra), with willingness to learn others as needed.
• Ability to deliver features independently, participate in design discussions, and collaborate with senior engineers on system architecture.
• Experience pair programming collaboratively with other developers
• Exposure to or interest in working with modern AI systems (LLMs, agent frameworks, cloud deployment). ML experience is a plus but not required.
• Nice to have: Experience with cloud deployment (Azure/AWS/GCP), containerization (Docker), frontend frameworks (React), CI/CD environments, and interest in agentic systems, LLMs, or workflow automation
• Demonstrated experience working collaboratively with other developers, as well as technical and non-technical people within software team
• Exceptional time management to meet your responsibilities in a complex and largely autonomous work environment.
• Strong communication skills, both verbal and written, in English and local office language(s), with the ability to adjust your style to suit different perspectives and seniority levels.