Software Development Engineer III - Conversations

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   Role Summary: We’re hiring a Senior Full Stack Engineer to design, build, and scale the backend systems and frontend interfaces that power the Threads & Composer experience inside HighLevel Conversations. You’ll spend most of your time on backend and API design, data flows, and performance — while still owning the Vue 3 UI layer end-to-end. Your work will touch critical paths that process billions of messages per month, demanding reliability, throughput, and correctness at scale.   Team & System Overview: The Conversations organization powers multi-channel communication across SMS, Email, WhatsApp, and DMs — handling over 2B messages each month. The Threads & Composer team owns the inbox and composer surfaces, and the backend services that deliver and store those interactions.You’ll work across Node.js microservices, GCP-based infra (GKE, Pub/Sub, Cloud Tasks), and MongoDB/Firestore storage layers, ensuring every message and UI state stays consistent, fast, and recoverable. Responsibilities:

Backend ownership: Design and maintain Node.js/NestJS services for message storage, retrieval, and state sync

API design: Build well-typed REST contracts for Threads and Composer operations

Data layer work: Model and optimize MongoDB/Firestore schemas for high read/write volumes and atomic updates

Scalability & resilience: Implement queues, caching, and rate limiting to handle burst traffic gracefully

Frontend integration: Ship modular Vue 3 UIs that consume your APIs efficiently and handle realtime state updates

Observability: Instrument logs, metrics, and traces to monitor latency, error rates, and throughput

Testing discipline: Maintain high coverage across unit, integration, and contract tests

Production ownership: Participate in on-call, debug incidents, and drive post-mortem action items to closure

Collaboration & mentorship: Work closely with Product and Frontend leads while reviewing code and supporting junior engineers

Requirements:

4+ years of professional engineering experience, preferably backend-heavy full-stack work

Expert in Node.js and TypeScript; comfortable with NestJS or Express microservices

Proficient in Vue 3 or similar modern frontend frameworks

Strong understanding of API design, data modeling, and distributed system patterns

Experience with GCP (or AWS), containerization, and CI/CD automation

Hands-on with observability and production monitoring

Bonus: Pub/Sub or message queue experience; event-driven or domain-driven design background

Technical Environment:

Backend: Node.js, TypeScript, NestJS / Express, REST APIs

Frontend: Vue 3, TypeScript, Pinia, Vite / Webpack, Tailwind

Storage: MongoDB, Firestore, Redis

Infra: GCP (GKE, Pub/Sub, Cloud Tasks, Stackdriver)

CI/CD: GitHub Actions, Docker, Kubernetes

Testing: Jest, Vitest