Frontend Platform Engineer III

Ready to make a serious impact? Millions of people already rely on Calendly, and we’re still in the midst of exciting product growth — it’s a fantastic time to join us. Everything you’ll work on here will accelerate your career to the next level. If you want to learn, grow, and do the best work of your life alongside the best people you’ve ever worked with, then we hope you’ll consider allowing Calendly to be a part of your professional journey.

We power Calendly's products with reliable, high-performance calendar data infrastructure. Our services provide the foundation for how users interact with their scheduling data, serving as the single source of truth across our platform.

As a Frontend Platform Engineer on Calendly’s App Platform team, you will be instrumental in building the foundational capabilities that power our product ecosystem. Your work will directly impact how our engineering teams ship features and the quality of experience they deliver to millions of Calendly users..

You will focus on critical platform services including:

• Shared frontend packages which are used in numerous frontend web applications
• Frontend architecture and shared application scaffolding used as the foundation for new products
• Real-time UX Infrastructure to enable server-to-client data delivery to support dynamic and responsive experiences
• Developer tooling and observability infrastructure to improve engineering velocity and frontend reliability.

We're at an inflection point. As Calendly continues to scale, our product teams need increasingly sophisticated frontend platform capabilities to move quickly without sacrificing quality. In this role, you’ll help evolve our shared React architecture, package ecosystem, and developer experience. You’ll contribute to engineering standards, strengthen the reliability of our frontend infrastructure, and build the resilient tooling and migration paths our growing platform demands. Your technical collaboration will help shape not only what we build, but how we build across Calendly engineering.

Design, develop, and maintain the services and frameworks that product teams depend on. You will work hands-on with technologies like React and Webpack to build highly resilient, scalable systems; from real-time server-to-client data infrastructure to shared frontend services.

Contribute to significant projects from concept to production. Whether it’s building and launching real-time server-to-client infrastructure, optimizing package performance, or designing new platform capabilities, you will deliver high impact solutions with quality and reliability at the forefront.

Partner with product managers, designers, and engineering teams across Calendly to translate their needs into robust platform solutions that serve the entire organization. You will be a connector across teams, building relationships with product engineers and acting as a trusted liaison who advocates for platform solutions that make their work easier.

Ensure reliability and performance of platform services through thoughtful monitoring, testing, and incident response. Participate in on-call rotation to support business-critical systems and drive continuous improvement based on operational learnings. 

• 3+ years of software engineering experience at a SaaS or technology company, with a strong focus on modern frontend architecture
• Strong proficiency in React, TypeScript, and Webpack (or comparable build tooling), including application architecture, dependency management, and performance optimization
• Experience designing and maintaining shared frontend platforms, libraries, and infrastructure used across multiple teams
• Experience with package ecosystems (versioning, upgrades, migrations, and compatibility across apps)
• Experience building systems and processes that keep frontend dependencies up to date, stable, and aligned across teams
• Ability to partner with product engineering teams to improve application architecture, performance, and maintainability in React apps
• Strong debugging skills, with experience diagnosing cross-app issues spanning packages, build systems, runtime behavior, and CI/CD pipelines
• Experience supporting large-scale migrations (e.g., library upgrades, architectural shifts, routing changes, state management transitions)
• Familiarity with CI/CD pipelines, release workflows, and automation for frontend packages and applications
• Strong communication skills, able to collaborate with design system teams, product engineers, and infrastructure partners
• Authorized to work lawfully in the United States of America as Calendly does not engage in immigration sponsorship at this time

• Background in platform engineering, developer experience (DevEx), or internal tools roles
• Experience with micro-frontend (MFE) architecture, including module federation, build, deployment, and integration pipelines
• Experience authoring shared packages from scratch (e.g. datetime utilities, SSE / Server-Side Event clients, custom eslint rules)
• Experience with RTK Query cache architecture, including cache tags, optimistic updates, and strongly-typed API layers
• Experience with Storybook infrastructure and migrations, including CI integration and version upgrades
• Experience with analytics, experimentation, or feature flagging SDKs/infrastructure

• You appreciate system-level thinking and building frameworks and abstractions that make the right way the easy way for other engineers
• You are passionate about shared frontend infrastructure and treat it as a product; improving reliability, clarity, and long-term sustainability. 
• You contribute to reducing single points of failure across our React ecosystem, ensuring platform knowledge is shared and durable.
• You build systems that keep our packages modern and aligned—dependency upgrades, migration paths, tooling improvements, and CI/CD automation.
• You partner with product teams to improve architecture, performance, and maintainability in their React apps. 
• You thrive in collaborative environments and are energized by enabling others to ship with confidence
• You are comfortable navigating ambiguity that spans build tooling, shared packages, runtime behavior, and deployment pipelines.
• You collaborate closely with our Design System engineers, complementing their component work by strengthening the platform foundation those components rely on.
• You communicate clearly and confidently, helping teams understand architectural trade-offs and guide migrations collaboratively rather than prescriptively. 
• You lead with curiosity and assume positive intent, approaching cross-team collaboration and technical disagreements with empathy and a bias toward shared understanding.

This role may require occasional travel for company events, team collaboration, or offsites.