Senior Backend Engineer - Users

About HighLevel:HighLevel is an AI-powered business operating system that gives agencies, entrepreneurs and SMBs the infrastructure to build, automate and scale. Today, HighLevel supports SMBs across 150+ countries, fueling community-driven growth rooted in real customer outcomes. To date, businesses operating on HighLevel have generated over $7 billion in ecosystem value, demonstrating the impact of shared infrastructure at scale. By centralizing conversations, automation and intelligence into one system, we help businesses move faster, reduce complexity and execute efficiently. Behind the platform, HighLevel powers more than 4 billion API hits and 2.5 billion message events daily. With 250 terabytes of distributed data, 250+ microservices and over 1 million domain names supported, our architecture is built for performance, resilience and long-term scalability. Our people With over 2,000 team members across 10+ countries, HighLevel operates as a global, remote-first organization built for speed and ownership. We value initiative, clarity and execution, creating space for ambitious people to build systems that support millions of businesses worldwide. Here, innovation thrives, ideas are celebrated and people come first, no matter where they call home. Our impact Every month, HighLevel enables more than 1.5 billion messages, 200 million leads and 20 million conversations for the more than 1 million businesses we support. Behind those numbers are real people building independence, expanding opportunity and creating measurable impact. We’re proud to be a part of that. Learn more about us on our YouTube Channel or Blog Posts     About the Role We’re looking for a seasoned Senior FullStack Engineer (SDE III) to join our Users Module team, where you'll design and build scalable, secure user management systems. This includes working on authentication, authorization, and complex permission hierarchies across a multi-tenant SaaS platform.You’ll collaborate cross-functionally to deliver reliable, performant, and secure experiences for millions of users.   This role is ideal for someone who thrives in product-oriented backend systems, has a strong full stack foundation, and is comfortable using AI tools to enhance their development speed and effectiveness. Responsibilities:

Write clean, maintainable code in TypeScript/JavaScript

Build and maintain robust RESTful APIs for user management and authentication

Design scalable multi-tenant user data models and schemas

Implement OAuth, JWT, and secure session management

Design and implement IAM v2 systems with RBAC and granular permissions

Build features like user impersonation, delegation, and permission templates

Create and manage token validation and session lifecycle flows

Architect scalable models using MongoDB, Firestore, and SQL

Integrate Elasticsearch for advanced user search and filtering

Sync user data across multiple stores and implement audit logging

Build secure auth flows with encryption, token validation, and data privacy controls

Ensure compliance with GDPR and similar regulations

Create audit trails and compliance reporting for user actions

Optimize queries, implement caching strategies, and handle high-volume user operations

Build systems that scale across enterprise-grade customer environments

Partner with product, security, and platform teams to deliver features

Collaborate with DevOps on deployment and infrastructure

Mentor junior engineers and participate in architecture discussions and code reviews

Required Candidate Profile:

4+ years in backend engineering, preferably building user management systems

Proven work on authentication/authorization and IAM systems

Experience with multi-tenant SaaS and enterprise user workflows & permissions

Required Technical Skills

Languages: TypeScript, JavaScript, Node.js

Frameworks: NestJS, Express.js

Databases: MongoDB, Firestore, SQL

Authentication: OAuth 2.0, JWT, session management

Cloud: Google Cloud Platform (GCP)

Messaging: Google Cloud Pub/SubDevOps: Git, CI/CD

Search: Elasticsearch, Clickhouse

Architecture: Microservices, Event driven architecture, IAM, RBAC