Backend Engineer (LLM / AI Experience)

We’re looking for a Senior Backend Engineer with recent LLM product experience who combines strong architectural thinking with hands-on development. You’ll work closely with the Head of Engineering, playing a key role in technical decisions while remaining deeply involved in day-to-day coding, feature delivery, and system optimization. You’ll be a senior technical voice on the team - someone who designs systems and builds them. ️ What You’ll DoArchitecture & System Operations (50%)

• Actively participate in architectural decisions with the Head of Engineering
• Collaborate with the Cloud Infrastructure Engineer on platform architecture, observability (monitoring, logging, alerting), and deployment strategies
• Design and optimize systems: performance profiling, database queries, caching, and resource usage
• Own production operations: troubleshooting, incident response, and on-call
• Provide technical guidance through code reviews, design discussions, and best practices

• Collaborate on real-time streaming architecture with the Video Synthesis Engineer Feature Development & Implementation (50%)

• Implement backend features and services in production-grade Python and Go
• Build conversation features: state management, history, and intelligence improvements
• Implement multi-document knowledge bases using AWS Bedrock
• Integrate LLM APIs (OpenAI, AWS Bedrock) and build RAG pipelines
• Develop APIs and service integrations (gRPC, REST)
• Work on core backend services: orchestration, caching, and platform APIs

• Own testing, CI/CD pipelines, and deployment automation Tech Stack

• Python (FastAPI) and Go (gRPC services)
• AWS (S3, EC2, Lambda, Bedrock, managed services)
• Docker, Kubernetes, RabbitMQ, Redis
• LLM APIs (OpenAI, AWS Bedrock), + Backend systems you’ve built and maintained
• LLM features you’ve implemented in production
• A performance optimization project you worked on
• Your experience with RAG or knowledge bases
• Why digital humans excite you Apply via the Easy Apply button, or reach out directly to joyce@unith.ai - creativity is welcome Recruitment Process

1. Intro call with Joyce (30 min)
2. Technical interview with Head of Engineering & Product Manager (90 min)
3. Team meeting with backend video synthesis, and/or infrastructure engineers (90 min)
4. Practical exercise (short, relevant implementation task)
5. Reference check ️ Timeline: 2-3 weeks from application to offer Ready to make digital humans faster, better, and more reliable? Apply now Inscribirse en esta oferta Recibir ofertas similares por correo electrónico Al crear una alerta, aceptas nuestros Términos y condiciones y Política de privacidad, y el uso de cookies.

• 5+ years of backend engineering experience with distributed systems, microservices, and real-time architectures (WebSocket, gRPC, event-driven)
• Experience building and deploying complex, highly-performant Python applications
• 2+ years building LLM-powered products in production (2022-2025), including hands-on experience with LLM APIs (OpenAI, Anthropic, AWS Bedrock) and RAG systems
• Comfortable balancing architecture design with hands-on implementation
• Strong AWS experience with focus on performance optimization, observability, and production operations
• Proven ability to optimize production systems (latency, throughput, technical debt)

• Excellent collaboration skills across backend, infrastructure, and AI/ML teams Bonus Points

• Golang experience
• Experience with video streaming, media processing, or conversational AI platforms
• Data engineering or ML model serving infrastructure experience

First 6 months

• Knowledge transfer completed and ownership of critical backend services established
• Multi-document knowledge base and conversation features live in production
• Active contributor to architecture discussions with measurable performance improvements

• Production systems well-monitored with improved observability First 12 months

• Core backend services and RAG pipeline running reliably in production
• Platform-wide performance optimizations delivered (Q1-Q3 targets met)
• Backend engineers unblocked and supported through your technical guidance

• Recognized as the go-to expert for backend + LLM implementation What We OfferCompensation & Flexibility

• Salary: €50,000 - €65,000, depending on experience

• Hybrid work in Barcelona or remote options within Europe Impact & Growth

• Ownership of critical backend services used daily by enterprise customers
• Hands-on technical work alongside architectural responsibility
• Deep technical challenges across LLMs, RAG pipelines, real-time systems, and scalability
• High-impact role in a small, senior team (12 people)
• Close collaboration with Engineering, AI research, and infrastructure teams
• Opportunity to build expertise in the fast-evolving digital humans domain Additional Perks ️ Office in the center of Barcelona Work from anywhere ️ Lunch compensation when in the office Private health insurance with Alan Travel allowance (for team members living 10km+ from the office) Flexible benefits (tax-free under Spanish legislation) ️ ClassPass discount

About UNITH At UNITH, we’re transforming customer journeys with conversational AI. Listed on the ASX, we create lifelike digital humans using cutting-edge synthetic facial movement, voice engineering, and conversational design. Our digital humans speak 60+ languages with 600+ voices, redefining how businesses interact with customers worldwide.