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