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Linktree is seeking a Senior Full Stack Engineer to join the Auth team, which owns authentication and identity for 70+ million users. This is a critical, high-impact role focused on building and maintaining the login, signup, and session management systems that every Linker encounters first.
You will own the complete authentication surface end-to-end: signup and login flows, social authentication, account recovery, multi-factor authentication, session and token lifecycle management, rate limiting, and the APIs that other teams depend on. You'll work across the full stack—TypeScript, Node.js, React, GraphQL, PostgreSQL/MySQL, and AWS—shipping features that span frontend UI through backend services and infrastructure.
Key responsibilities include:
- Building and shipping authentication and identity experiences (signup, login, social auth, account recovery, MFA)
- Owning backend services end-to-end: session/token lifecycle, revocation, rate limiting, and cross-team APIs
- Partnering with Security to harden the auth surface and with Product to optimize login conversion
- Extending identity and access for business accounts and Workspaces, including SSO roadmap
- Implementing observability: instrumentation, alerting, and dashboards to catch auth failures proactively
- Leveraging AI tools to accelerate migrations, testing, and investigation
- Mentoring engineers and raising engineering standards through code review, pairing, and documentation
Linktree operates globally with offices in London, Los Angeles, Melbourne, and San Francisco. The company has grown to 70+ million users, with 48,000 new accounts created daily. You'll work in a flexible, async-first culture with hybrid options in Melbourne or Sydney.
REQUIREMENTS:
- 4+ years of professional software engineering experience, ideally including time on auth, identity, platform, or payments-adjacent teams
- Solid full-stack skills: TypeScript, Node.js, React, GraphQL, PostgreSQL or MySQL, AWS, with ability to ship features end-to-end across layers
- Working knowledge of authentication fundamentals: OAuth 2.0, OIDC, JWTs, session management, MFA, and common attack classes
- Experience shipping changes to high-traffic, critical-path systems safely: feature flags, staged rollouts, migrations, backwards compatibility
- Fluency with AI-assisted development (Claude, Cursor, Codex, etc.), including prompting, validation, and refinement
- Pragmatic instinct for balancing security against user experience; confidence to make trade-offs explicit with Product and Security
- Clear communicator who works well with product, design, and security partners across time zones
- Able to work from Melbourne or Sydney office on a hybrid basis
