Software Development Engineer III (Full Stack) - Agency Experience

About Us 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 Senior Software Engineer to join our Agency Module and Billing Team, which powers the foundation of our Agency Ecosystem — enabling seamless onboarding, management, and monetisation experiences for HighLevel’s agencies and their clients. Today, over 100K agencies run their businesses with HighLevel, collectively serving 2M+ businesses of all scales — primarily SMBs. The Company Module and Agency Billing systems are at the heart of this growth, helping agencies onboard faster, manage finances effortlessly, and scale their operations with reliability and transparency. This team builds and scales key components like Agency Signup, Agency Billing, and the HighLevel Affiliate Program, all integrated into our whitelabeled platform that empowers businesses to deliver customised experiences under their own brand. These systems are critical to the growth and sustainability of HighLevel’s ecosystem — supporting thousands of agencies and their downstream customers with robust, scalable, and secure infrastructure. As a Senior Software Engineer, you’ll play a pivotal role in designing and evolving these core systems. You’ll work on challenges across frontend and backend architecture, distributed systems, payment integrations, and multi-tenant SaaS design — ensuring reliability, scalability, and a seamless experience for agencies across web and mobile platforms. You’ll collaborate closely with Product Managers, Designers, and other Engineers to deliver powerful and intuitive solutions that help agencies scale faster and manage their businesses effortlessly.

Responsibilities

• Own and contribute to architecture and development across Agency Module, Billing, and Affiliate systems, driving technical excellence across frontend and backend services.
• Design and implement robust backend APIs for subscription management, payments, invoicing, and affiliate tracking, using test-driven development and scalable distributed patterns (caching, messaging, queuing).
• Deliver performant frontend experiences for agency onboarding, billing dashboards, and affiliate management using modern frameworks and component-driven architecture with strong state management principles.
• Architect secure integrations with third-party payment gateways (e.g., Stripe) and internal microservices, ensuring accuracy, reliability, and compliance in all financial transactions.
• Implement and maintain observability, logging, and monitoring to ensure high availability and rapid incident resolution across critical billing and agency workflows.
• Champion platform security and compliance by enforcing best practices across authentication, authorization, data protection, and rate-limiting — ensuring the integrity of sensitive financial and user data.
• Leverage LLMs and AI-assisted tools to accelerate development, automate testing, refactoring, and documentation, while maintaining strong reliability guardrails.
• Collaborate cross-functionally with Product Managers, Designers, and other Engineering teams to ensure alignment between business goals and technical architecture.
• Participate in technical reviews, deep dives, and on-call rotations, fostering a culture of accountability, operational excellence, and continuous improvement.

Requirements

• 4+ years of hands-on software engineering experience building and scaling robust backend systems and high-performance frontend applications.
• Strong backend engineering and distributed system design skills, with hands-on experience in API development, data modeling, and systems architecture using Node.js (NestJS preferred), TypeScript, PostgreSQL, MongoDB, and Redis.
• Expertise in backend performance optimization, caching strategies, and event-driven architectures (e.g., Redis, Kafka, Pub/Sub).
• Familiar with modern frontend frameworks (React, Vue, Angular), advanced UI engineering patterns, and CSS libraries like Bootstrap or Tailwind CSS.
• Advanced experience with complex state management libraries (e.g., Redux, Vuex, MobX) and architectural design of large-scale application state.
• Proven track record of optimizing frontend performance and web vitals at scale, including experience with server-side rendering (SSR), edge, or hybrid rendering architectures.
• Familiarity with frontend and backend observability - including monitoring, tracing, error tracking, and performance profiling in production (e.g., Grafana, Prometheus, Sentry, PostHog).
• Strong understanding of security best practices across the full stack—including authentication, authorization, access control, secure data flow, and privacy compliance.
• Excellent communication and cross-functional collaboration skills, able to drive complex initiatives, lead technical discussions, and mentor junior engineers.

EEO Statement: At HighLevel, we value diversity. In fact, we understand it makes our organisation stronger. We are committed to inclusive hiring/promotion practices that evaluate skill sets, abilities, and qualifications without regard to any characteristic unrelated to performing the job at the highest level. Our objective is to foster an environment where really talented employees from all walks of life can be their true and whole selves, cherished and welcomed for their differences while providing excellent service to our clients and learning from one another along the way! Reasonable accommodations may be made to enable individuals with disabilities to perform essential functions. We encourage you to review our Privacy Policy before submitting your application. We may use artificial intelligence (AI) tools to support parts of the hiring process, such as reviewing applications, analyzing resumes, or assessing responses and identifying potential inconsistencies or verification signals in application materials based on available information. These tools assist our recruitment team but do not replace human judgment. Final hiring decisions are ultimately made by humans. If you would like more information about how your data is processed, please contact us.