Senior FullStack Engineer - CRM Users at HighLevel

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 EEO Statement: The company is an Equal Opportunity Employer. As an employer subject to affirmative action regulations, we invite you to voluntarily provide the following demographic information. This information is used solely for compliance with government recordkeeping, reporting, and other legal requirements. Providing this information is voluntary and refusal to do so will not affect your application status. This data will be kept separate from your application and will not be used in the hiring decision. #LI-Remote #LI-HB1