Senior Full Stack Developer

Company: Hypefy Location: On-site/Hybrid (Zagreb) Type: Full-time Intro Hi - were Hypefy, a Croatian-based start-up. Were building AI agents that run influencer marketing end-to-end: campaign creation, creator selection, outreach, content checks, payments, reporting - all automated, all at scale. We want to make influencer marketing so efficient that spending your budget anywhere else stops making sense. This is already live, used by real brands and creators across more than 35 countries. Now we want to scale globally, and we need another strong engineer to help us get this right. What you'll work on Youll build and evolve core product features across backend and frontend, with direct exposure to AI workflows, campaign automation, and scaling infrastructure. Backend (Primary Focus) Design, build, and maintain backend services using Node.js Take features from idea production monitoring iteration Architect and operate background job systems (queues, workers, retries, fallbacks, failure handling) Ship AI-driven features with strong guardrails: schema validation, retries, and safe fallbacks Integrate, harden, and monitor third-party services for reliability and scale Make MongoDB fast and predictable through good data models and indexing Use Redis / BullMQ for queues, caching, rate limits, and transient state Frontend Build and refine UI features for both mobile and web (React) Surface system state clearly (background jobs, AI progress) Collaborate closely with design and product on usability for complex workflows Platform & Reliability Improving observability (logs, metrics, traces) so debugging doesnt feel like guesswork Contribute to scalability initiatives (regional deployments, throughput improvements) Participate in incident response and postmortems Help automate operational workflows (payments, reconciliation, support tooling) How We Work Small, senior-leaning engineering team High ownership, low bureaucracy Youll talk directly with product and founders We utilize a lot of AI coding tools for code reviews, small features/bugfixes etc. What Were Looking For Required Strong Node.js experience Experience with frontend js frameworks Comfort with async systems, background jobs, and failure scenarios Comfortable owning features end-to-end (backend + frontend integration) Comfortable making technical and product decisions (in line with established standards) with incomplete information, without needing every detail handed to you Comfortable using technical debt intentionally, and disciplined about cleaning it up Experience working with production systems that handle real users and failures Some experience with MongoDB (schema design, indexing, performance) Clear communication and strong ownership mindset Nice to Have Strong experience with React Experience in Python Experience with AI / LLM integrations in production, and AI libraries Experience utilizing advanced AI coding workflows Prior work in SaaS, marketplaces, or workflow-heavy platforms Why Join Hypefy Youll work on complex, sometimes messy systems, and help make them better Small, agile engineering team where input is not only allowed, but expected Pragmatic engineering culture Work on a real AI product, that aren't just a bolt-on, used in live customer workflows Direct impact on architecture and scaling decisions Interview Process Intro call (context + expectations) Live interview Offer