Senior backend engineer

Role: Senior backend engineer Job Ref Id: JD-1262 Competence level: 5+ years Start date: 2026-11-02 End date: 2027-04-30 Extension option: Yes Scope: 100% Location: Stockholm Remote work: On-site Language: English Application deadline: 2026-10-25 Number of consultants: 1 Security clearance: No About the assignment We are looking for an experienced backend engineer with expertise in Node.js and MongoDB to work on one of our core products. Responsibilities Develop and maintain Node.js applications Deploy and release new capabilities, features and fixes Ensure quality standards, including test automation, manage tech debt, etc. Collaborate with product managers to define the product roadmap Write and maintain tech documents, including RFCs, ADRs, postmortems, etc. Own tech roadmap and priorities aligning with product priorities Ensure observability and monitoring match industry standards Proactively address security issues in collaboration with our security department Join and actively contribute to team ceremonies Propose improvements in our SDLC Proactively identify cost saving opportunities Requirements Mandatory Solid experience with TypeScript/JavaScript/Node.js and MongoDB (Mongoose ODM) Experience with real-time/streaming systems design (e.g. WebSockets, low-latency audio pipelines, etc.) Hands-on experience with Redis / ioredis (caching, rate limiting, pub/sub) Experience with event-driven applications and messaging systems Solid experience with microservices architecture and async programming Experience with observability/metrics tooling (e.g. Prometheus, structured logging) Nice-to-have Experience with BullMQ and Node's Cluster module, working with workers and subprocesses Experience with LLMs and audio processing (STT/TTS) Experience with Keystone and Express.js Experience with gRPC and Protocol Buffers Experience with NATS (messaging queue) Experience with Docker and Docker Compose Experience with Kubernetes + ArgoCD + Kustomize (multi-region GKE deployments) Experience with Go and WebSocket bridging services Experience with cloud/VoIP telephony and telecom generally Experience with Kamailio / Homer Experience with Asterisk PBX / ARI (Asterisk REST Interface) and SIP/IAX protocols Experience with Firebase Admin / APNs