Senior Node.js Backend Engineer (APIs & Integrations) - English Required Remote

About Halcyon Labs At Halcyon Labs , we build high-impact software solutions for startups and global companies across LATAM and the U.S. We work with senior engineers who take ownership of their work, care about production quality, and thrive in collaborative, fast-moving environments. Role Overview We are looking for a Senior Backend Engineer with a strong focus on integrations and distributed systems, capable of designing, implementing, and maintaining robust, scalable, and secure backend systems using Node.js and NestJS. This is not a configuration or low-code role. You will be embedded in a senior engineering team, working directly with a U.S.-based client in English on a daily basis. We expect deep understanding of backend engineering — protocols, concurrency, security, and real production systems. Why this role is interesting Work on complex backend systems with real-world integrations (SaaS platforms, payment APIs, ERPs) Solve challenges around scalability, reliability, and distributed systems Collaborate with a highly senior team with strong technical ownership Work directly with U.S.-based engineering teams — in English, daily What You'll Do Design and build scalable backend services using Node.js + NestJS Develop and maintain robust, secure REST APIs and internal services Work on integrations between SaaS platforms, payment/notification services, and internal systems Implement event-driven flows (webhooks, retries, idempotency) Contribute to authentication and authorization flows (OAuth2, JWT, API keys) Identify and solve performance, concurrency, and scalability challenges Improve observability, logging, and error handling in production Own technical decisions and contribute to architecture discussions Requirements 4+ years developing backend systems in production environments Strong hands-on experience with Node.js + NestJS in production Experience building and consuming APIs (REST, webhooks, third-party integrations) Experience integrating with external SaaS platforms or services (payment, notifications, data pipelines, or similar) Solid understanding of authentication and authorization (OAuth2, JWT or similar) Strong grasp of backend fundamentals: performance, scalability, reliability, error handling Advanced English — you will work directly with U.S.-based teams and clients on a daily basis Nice to Have Experience with iPaaS tools (Workato, Mulesoft, Boomi, or similar) Experience integrating with ERPs (NetSuite, SAP, Business Central) Experience with high-concurrency or high-throughput systems Familiarity with cloud platforms (AWS, GCP, or Azure) CI/CD practices and DevOps awareness How We Work Remote-first culture across LATAM High ownership and autonomy — we expect engineers to lead, not just execute Focus on clean, maintainable, production-grade code Senior-level environment with direct impact on product and architecture decisions Benefits 🚀 Work with global brands and disruptive startups . 🏡 Remote work / Home office . 📍 If a hybrid or on-site model is required, you will be informed from the first session. ⏳ Work schedule aligned with the assigned project/team . 📅 Monday to Friday schedule . ⚖️ Legal benefits (Applicable for Mexico) . 🎉 Day off on your birthday . 🏥 Private health insurance (Applicable for Mexico) . 🛡️ Life insurance (Applicable for Mexico) . 🌎 Multicultural teams . 🎓 Access to courses and certifications . 📢 Meetups with industry experts and top universities . 📡 Virtual networking events and interest groups . 📢 English classes . 🏆 Opportunities within our different business lines . 🏅 Proudly certified as a Great Place to Work . Originally posted on Himalayas