Senior Frontend Platform Engineer, App Platform

What’s in it for you? 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. About the team & opportunity Our Mission 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. How you will contribute As a Senior 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. Why this role matters 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 define and 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 leadership and collaboration will shape not only what we build, but how we build across Calendly engineering. A day in the life of a Senior Frontend Platform Engineer at Calendly Building Platform Infrastructure 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. Technical Leadership and Collaboration Contribute to architectural decision and technical strategy for the platform that drives the look and feel of our frontend. Provide guidance to engineers across the organization, share your expertise in frontend platform systems, and help establish patterns and practices that raise the bar for engineering excellence. Contribute To Critical Initiatives Own and 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. Cross-Functional Partnership 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. Operational Excellence 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. What do we need from you? 6+ years of software engineering experience at a SaaS or technology company, with a strong focus on modern frontend architecture Deep expertise 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 Proven ability to own and evolve 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 Comfortable acting as a force multiplier: unblocking teams, providing architectural guidance, and reducing single-points-of-failure in the frontend ecosystem 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 Bonus 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 What will make you successful here You think in systems and build frameworks and abstractions that make the right way the easy way for other engineers You take ownership of shared frontend infrastructure and treat it as a product; improving reliability, clarity, and long-term sustainability. You proactively identify and reduce 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. You invest in the people around you, sharing knowledge generously, mentoring engineers across the organization, and celebrating others' growth as your own success. Tier 1 Salary Hiring Range $224,400 - $283,800 USD Tier 2 Salary Hiring Range $205,700 - $260,150 USD Tier 3 Salary Hiring Range $187,000 - $236,500 USD The ranges listed above are the expected annual base salary for this role, subject to change. Calendly takes a number of factors into consideration when determining an employee’s starting salary, including relevant experience, relevant skills sets, interview performance, location/metropolitan area, and internal pay equity. Base salary is just one component of Calendly’s total rewards package. All full-time (30 hours/week) employees are also eligible for our Top Performer Bonus program (or Sales incentive), equity awards, and competitive benefits. Calendly uses the zip code of an employee’s remote work location, or the onsite building location if hybrid, to determine which metropolitan pay range we use. Current geographic zones are as follows: Tier 1: San Francisco, CA, San Jose, CA, New York City, NY Tier 2: Chicago, IL, Austin, TX, Denver, CO, Boston, MA, Washington D.C., Philadelphia, PA, Portland, OR, Seattle, WA, Miami, FL, and all other cities in CA. Tier 3: All other locations not in Tier 1 or Tier 2 If you are an individual with a disability and would like to request a reasonable accommodation as part of the application or recruiting process, please let your Recruiter know when first connecting with them. Calendly is registered as an employer in many, but not all, states. If you are located in Alabama, Alaska, Delaware, Hawaii, Idaho, Iowa, Montana, Nebraska, North Dakota, Rhode Island, South Dakota, and West Virginia, you will not be eligible for employment. Note that all individual roles will specify location eligibility. All candidates can find our Candidate Privacy Statement here Candidates residing in California may visit our Notice at Collection for California Candidates here: Notice at Collection This role may require occasional travel for company events, team collaboration, or offsites.