Sr. Fullstack Engineer, Identity Platform

AI AT ZAPIER At Zapier https://zapier.com/about, we build and use automation every day to make work more efficient, creative, and human. So if you’re using AI tools while applying here - that’s great! We just ask that you use them responsibly and transparently. Check out our guidance on How to Collaborate with AI During Zapier’s Hiring Process https://zapier.com/l/jobs/ai-at-zapier, including how to use AI tools like ChatGPT, Claude, Gemini, or others during our hiring process - and when not to. Job Posted: March 17, 2026 Updated: April 29, 2026 Location: Americas - North, Central and South America Zapier is building the foundational systems that enable users and services to securely interact across our platform. As a Senior Fullstack Engineer on the Identity Platform team, you’ll design and scale the systems that define and enforce access across Zapier — from permissions and policies to OAuth/JWT infrastructure and service-to-service authentication. This is a high-impact platform role: you’ll shape how access is modeled, enforced, and scaled across Zapier, establishing consistent patterns that power secure interactions across a large, distributed system. The systems you build will be used by many teams and services, forming the foundation for how authentication and authorization work across the company. Your work will directly support Zapier’s core product strategy and influence how access is enforced at scale, enabling secure automation, enterprise-grade governance, and the next generation of capabilities across the platform. ABOUT YOU - You’re an experienced fullstack or platform engineer who has built real-world authentication and authorization systems at scale. You’ve helped define or evolve IAM platforms—not just used them—through collaboration across engineering, product, and other stakeholders. You bring experience with OAuth, JWTs, token-based authentication, and service-to-service auth, and are comfortable working with modern permission models such as RBAC, ABAC, or relationship-based access control. - You think in platforms, not features. You’ve built shared systems other teams depend on, and understand how to design stable APIs, manage breaking changes, and maintain strong boundaries as systems scale. You have solid systems instincts and consistently consider security, scalability, and correctness in your designs. - You’re comfortable working across the stack. This is a fullstack role on a platform team—you’ll primarily build backend systems, but also contribute to developer-facing UIs and tooling when needed. You don’t need to be an expert in every layer, but you’re not blocked by any of them. - You move quickly and work well in ambiguity. You believe building enterprise-grade systems can be both fast and secure, and you use that mindset to ship working solutions early, using prototypes to drive alignment rather than waiting for perfect specs. You’re comfortable iterating, discarding work when needed, and treating it as part of the learning loop. - You use AI agents as a core part of your workflow, leveraging them to explore codebases, accelerate development, and prototype solutions quickly. You understand their limitations, continuously refine your approach, and help others on your team work more effectively with them. - You operate with strong ownership and communication. You take initiative, work transparently in an async environment, and keep stakeholders informed without being asked. You’re comfortable engaging directly with both internal engineering teams and enterprise customers, and you use written artifacts, prototypes, and demos to influence and drive clarity and alignment. THINGS YOU'LL DO - Be a thought leader in the Identity domain, helping to set the vision for our platforms to enable Zapier’s engineering teams to move fast and securely - Partner with Product and Engineering leadership to define and implement Zapier’s Governance strategy. Evolve Zapier’s IAM platform to provide consistent, reliable c