Principal Engineer - Platform Architecture & Core Reliability

About Quizlet :

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.

Let’s Build the Future of Learning

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

About the Role :

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.

We’re happy to share that 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 :

• Platform Reliability (SLO Focus) : 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.
• Data Backbone Scaling : Define the architectural approach for scaling our core data systems, optimizing performance across Cloud Spanner, PlanetScale MySQL, and BigQuery.
• Compute & Service Mesh : Drive performance and efficiency improvements across our managed compute environment, specifically optimizing Kubernetes (GKE) clusters and managing the performance and operational complexity of Istio.
• Developer Velocity & CI / CD : 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.
• Incident & Learning Culture : 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.
• Performance & Cost Engineering : 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 :

Compensation, Benefits & Perks :

Why Join Quizlet?

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!

In Closing :

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!

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