Senior FullStack Engineer - CRM Users

About HighLevel: HighLevel is an AI powered, all-in-one white-label sales & marketing platform that empowers agencies, entrepreneurs, and businesses to elevate their digital presence and drive growth. We are proud to support a global and growing community of over 2 million businesses, comprised of agencies, consultants, and businesses of all sizes and industries. HighLevel empowers users  with all the tools needed to capture, nurture, and close new leads into repeat customers. As of mid 2025, HighLevel processes over 4 billion API hits and handles more than 2.5 billion message events every day. Our platform manages over 470 terabytes of data distributed across five databases, operates with a network of over 250 microservices, and supports over 1 million hostnames. Our People With over 1,500 team members across 15+ countries, we operate in a global, remote-first environment. We are building more than software; we are building a global community rooted in creativity, collaboration, and impact. We take pride in cultivating a culture where innovation thrives, ideas are celebrated, and people come first, no matter where they call home. Our Impact As of mid 2025, our platform powers over 1.5 billion messages, helps generate over 200 million leads, and facilitates over 20 million conversations for the more than 2 million businesses we serve each month. Behind those numbers are real people growing their companies, connecting with customers, and making their mark - and we get to help make that happen. 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