Sr. Fullstack Engineer, Identity Platform

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 Location: Americas - North, Central and South America Zapier's mission is to enable enterprise companies to build and maintain dependable AI workflows at scale. The Identity Platform team builds the golden path that every product team uses to deliver reliable, consistent, and secure experiences to these customers. Authentication, session management, and credential infrastructure are the foundation. Get them right, and every product team ships faster with confidence. We're hiring a Senior Fullstack Engineer to own this foundation, drive the strategic and architectural direction of this layer for years to come, and directly unlock our largest enterprise deals. WHAT YOU'LL WORK ON - Enterprise authentication infrastructure. You'll design and extend the systems that handle SAML SSO, SCIM provisioning, OAuth/OIDC flows, multi-factor authentication, login, sign-up, and secure session for organizations with thousands of users. That spans the full auth surface: SCIM-driven user provisioning and de-provisioning, invitation flows, 2FA setup, SSO-enforced login, domain capture for auto-routing new signups, and session hardening. Reliability, latency, and efficiency are non-negotiables; auth is the most critical-path system at the company. You'll make these systems faster, more resilient, and easier for other teams to integrate with. - User session auth across services. Zapier is a multi-service platform. You'll own how user sessions propagate across service boundaries; making sure authentication context is consistent, secure, and performant whether a request hits the monolith, a Node.js service, or a Go microservice. You'll evolve JWT validation, token exchange, and session tracking to handle the complexity of a growing service footprint. - Enterprise authentication controls and compliance. Enterprise customers need org-level authentication policy enforcement: forced SSO, domain capture, admin-managed authentication requirements, and credential lifecycle controls like JWT key rotation, token refresh, and session expiry policies. You'll build and extend the APIs that give admins confidence their organization meets their security standards. SOC 2 access control evidence, GDPR data subject requests, and audit trail requirements are design constraints you'll work within regularly, not afterthoughts. - Platform APIs that other teams depend on. Identity is infrastructure. Your APIs, libraries, and contracts are consumed by dozens of teams. You'll design for backward compatibility, clear documentation, and low integration friction. But shipping the API is half the job. You'll also drive adoption: writing integration guides, running migration paths, and embedding with product teams to help them use auth capabilities correctly. Internal engineering teams' needs carry the same weight as end-customer value. LEVEL This is a Senior Engineer role. Senior engineers at Zapier own outcomes end-to-end within their team and extend impact beyond it. You'll coordinate across ownership boundaries, shape technical direction for adjacent systems, and bring other engineers along with you. Our level definitions may look different from what you've seen elsewhere. We'll be transparent about leveling before you reach the final stages. ABOUT YOU - You've set the vision and built identity systems for enterprise SaaS at scale. Not configured them, built them. You have hands-on experience with S ... (truncated, view full listing at source)