Senior Backend Engineer

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🕒 June 11

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Castillians

WebsiteLinkedInAll Job Openings

51 - 200 employees

Founded 2006

Castillians is a company whose publicly available text is inaccessible without JavaScript; the provided content only shows a message asking the user to enable JavaScript. No information about the company's product, services, industry, or target customers can be determined from this text alone.

📋 Description

• Build, deploy, and manage the real-time communication backend to support live audio interactions • Orchestrate end-to-end sessions between end users and backend AI services • Integrate Azure Speech services (STT/TTS) and Azure OpenAI (LLMs) into real-time pipelines • Develop and maintain REST and WebSocket APIs consumed by mobile and web frontends • Handle session state, participant matching, reconnections, and failure recovery as the “traffic controller” for calls • Ensure low-latency, highly available, and scalable infrastructure using containerized microservices • Build backend logic to manage call lifecycle (start/end sessions) • Match participants and track call state • Implement reconnection and failure-handling mechanisms • Act as the system’s “traffic controller” for real-time media sessions • Support for microservices architecture and API scaling

🎯 Requirements

• 5+ years of backend engineering experience • Strong background in distributed systems • Networking fundamentals (TCP/UDP, NAT, firewalls) • Cloud infrastructure (Azure preferred, but AWS/GCP experience considered) • Proven experience with WebRTC or similar real-time systems (e.g., SIP, RTMP, low-latency streaming) • Experience integrating AI/LLM services into production backends • Ability to work autonomously and mentor junior engineers as needed • Deep understanding of WebRTC connectivity (NAT traversal, firewalls, corporate networks) • Experience with TURN server deployment and management for media relaying • Proficiency in one or more of: Node.js, Python, .NET • Ability to handle audio routing, recording, and optional voice transformations • Hands-on experience with media servers such as: Janus, Kurento, mediasoup

🏖️ Benefits

• Clear scope with no ambiguity over deliverables. • Opportunity for repeat engagements based on performance.