Principal Engineer - Platform Architecture & Core Reliability

Principal Engineer - Platform Architecture & Core Reliability

At Quizlet, our mission is to help every learner achieve their outcomes in the most effective and delightful way. Our $1B+ learning platform serves tens of millions of students every month, including two-thirds of U.S. high schoolers and half of U.S. college students, powering over 2 billion learning interactions monthly. We blend cognitive science with machine learning to personalize and enhance the learning experience for students, professionals, and lifelong learners alike. We're energized by the potential to power more learners through multiple approaches and various tools.

Join us to design and deliver AI-powered learning tools that scale across the world and unlock human potential.

We're hiring a Principal Engineer to lead critical architectural decisions that establish industry-leading standards for reliability and operational excellence. This is a high-leverage, hands-on role focused on optimizing performance, driving engineering velocity, and leading systemic architectural change. The role reports to the Senior Director of Technical Infrastructure. This is an onsite position in our San Francisco office. To help foster team collaboration, we require that employees be in the office a minimum of three days per week: Monday, Wednesday, and Thursday and as needed by your manager or the company. We believe that this working environment facilitates increased work efficiency, team partnership, and supports growth as an employee and organization.

In This Role, You Will:

• Lead the strategy and implementation necessary to achieve and maintain our 99.95% availability target. This includes evolving our multi-region deployment strategy and optimizing for resilience under sustained, high-volume traffic.
• Define the architectural approach for scaling our core data systems, optimizing performance across Cloud Spanner, PlanetScale MySQL, and BigQuery.
• Drive performance and efficiency improvements across our managed compute environment, specifically optimizing Kubernetes (GKE) clusters and managing the performance and operational complexity of Istio.
• Architect high-leverage internal platforms, designing the pipelines across tools like GitHub Actions, CircleCI, and ArgoCD, and driving organizational influence to standardize high-velocity, safe deployment practices.
• Drive reliability change across the engineering organization by leveraging deep-dive analysis of incidents (Jeli) and proactive monitoring (Datadog), improving operational practices, and influencing architectural design decisions.
• Act as a technical owner for the cost-per-request metric, identifying and implementing architectural efficiencies (caching, connection pooling, resource utilization) that scale down infrastructure spend while maintaining service speed.

What You Bring To The Table:

• Deep technical mastery and hands-on experience across three or more of the following high-leverage domains with 10+ years of experience in software development, site reliability engineering, or platform engineering.
• A proven track record of driving significant architectural outcomes as a Principal or Staff Engineer in a high-scale platform or infrastructure role.
• A history of scaling consumer-facing systems that reliably handle tens of thousands of requests per second (RPS) and successfully achieving high-availability targets across multi-region cloud environments.
• Deep expertise in architecting and optimizing complex data backbones involving transactional, globally consistent (e.g., Cloud Spanner / PlanetScale), and analytical systems (BigQuery).
• Strong operational knowledge of Kubernetes (GKE) orchestration layered with a Service Mesh (Istio), including traffic shaping, security, and performance tuning.
• Proven ability to design and implement automated CI/CD pipelines leveraging tools like GitHub Actions, CircleCI, and ArgoCD, with a track record of successfully deploying AI developer tools and workflows.
• Mastery in implementing comprehensive monitoring using Datadog for defining SLOs and performing deep-dive investigations, and a strong background in leading structured incident response using tools like Jeli.
• Extensive experience in designing and optimizing large-scale cloud-native architecture on GCP (or equivalent cloud providers), including network optimization (e.g., Cloudflare integration) and infrastructure cost management.

Compensation, Benefits & Perks:

• Quizlet is an equal opportunity employer. We celebrate diversity and are committed to creating an inclusive environment for all employees. Total compensation for this role is market competitive, including a starting base salary of $260,000 - $320,000, depending on location and experience, as well as company stock options.
• Collaborate with your manager and team to create a healthy work-life balance.
• 20 vacation days that we expect you to take!
• Competitive health, dental, and vision insurance (100% employee and 75% dependent PPO, Dental, VSP Choice)
• Employer-sponsored 401k plan with company match
• Access to LinkedIn Learning and other resources to support professional growth
• Paid Family Leave, FSA, HSA, Commuter benefits, and Wellness benefits
• 40 hours of annual paid time off to participate in volunteer programs of choice

Massive reach: 60M+ users, 1B+ interactions per week

Cutting-edge tech: Generative AI, adaptive learning, cognitive science

Strong momentum: Top-tier investors, sustainable business, real traction

Mission-first: Work that makes a difference in people's lives

Inclusive culture: Committed to equity, diversity, and belonging

We strive to make everyone feel comfortable and welcome!

We work to create a holistic interview process, where both Quizlet and candidates have an opportunity to view what it would be like to work together, in exploring a mutually beneficial partnership.

We provide a transparent setting that gives a comprehensive view of who we are!

At Quizlet, we're excited about passionate people joining our team—even if you don't check every box on the requirements list. We value unique perspectives and believe everyone has something meaningful to contribute. Our culture is all about taking initiative, learning through challenges, and striving for high-quality work while staying curious and open to new ideas. We believe in honest, respectful communication, thoughtful collaboration, and creating a supportive space where everyone can grow and succeed together.

Quizlet's success as an online learning community depends on a strong commitment to diversity, equity, and inclusion.

As an equal opportunity employer and a tech company committed to societal change, we welcome applicants from all backgrounds. Women, people of color, members of the LGBTQ+ community, individuals with disabilities, and veterans are strongly encouraged to apply. Come join us!