Software Development Engineer III - Fullstack

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 You’ll be joining our WordPress team, a group of dedicated engineers, creators, and support specialists who are passionate about building fast, reliable, and scalable digital experiences. Together, we help customers create high-performance websites on our managed hosting platform. Our team supports more than 20,000 businesses and delivers a seamless experience for millions of visitors every month. We collaborate closely, innovate constantly, and take pride in empowering businesses to grow online. As a Senior Software Engineer, you’ll be contributing in shaping the experience of our platform. You’ll solve complex challenges across frontend / backend architecture, performance, micro-frontends, and distributed backend systems. You’ll contribute to overall growth and stability of the platform, collaborate closely with PMs and ensure exceptional user experiences at scale. Responsibilities Own and contribute to architecture and development across products, driving technical excellence in both frontend and backend systems. Develop and optimize backend API services with test-driven development including advanced caching and messaging for reliability and scalability. Deliver high-quality frontend experiences using modern frameworks, with strong fundamentals in component-based architectures and state management. Integrate and support observability, logging, and monitoring to ensure platform reliability and rapid incident response. Ensure top-tier application security and compliance, applying best practices across frontend, backend, and API layers (authentication, authorization, rate-limiting, OWASP). Leverage LLMs and AI tools to write, refactor, test, and debug code efficiently, implementing guardrails for reliability. Participate in design reviews, deep dives, and on-call rotations to support a culture of accountability and operational excellence. 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, 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 ( Vue, Angular, React), 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 Polic y before submitting your application.