Senior AI Engineer (Hybrid in Ghent + Relocation support)

Ersilia; Oost-Vlaanderen; On-site; EUR 70,000 - 105,000; Full time

Job summary

Ersilia in Ghent, Belgium is seeking a Senior AI Engineer to help build an AI-powered sales assistant for field reps. You will work on agent harnesses, context management, multi-agent orchestration, and RAG systems.

Join a fast-growing startup with global ambitions; report to the co-founder & CTO, collaborating with Product, Design, and customers to define features and trade-offs that maximize value.

Qualifications

• At least 5 years of professional software engineering experience.
• Hands-on experience building and shipping LLM-powered features in a software product.
• Experience with TypeScript and Node.js.
• Good sense of AI interaction design and how AI should behave.
• Curious about product data and patterns, asking questions.
• Ability to break down big initiatives into smaller tasks.
• Ambition to thrive in a start-up culture.
• Must be fluent in English.

Responsibilities

• Build and improve LLM-powered features for our product.
• Develop and maintain agent harnesses with context management and feedback loops.
• Own features from problem understanding to rollout, balancing product and technical trade-offs.
• Integrate contextual data (e.g., CRM data, emails) to enrich LLM outputs.
• Explore product data to turn insights into better user experiences.
• Develop multilingual conversational algorithms and robust RAG systems.
• Ensure high-quality AI outputs with observability and testing.

Skills

LLMs

TypeScript & Node.js

Software engineering

AI interaction design

English fluency

Tools

Node.js

TypeScript

Job description

Please note: You must be able to work from the Ghent office; this is not a remote position.

The Role:

As a Senior AI Engineer, you'll be a vital part of our team, working together to build an AI-powered sales assistant for field sales reps, empowering them to focus on what they do best: selling.

Expect to navigate a wide range of challenges, including building reliable agent harnesses, managing context, orchestrating multiple AI agents, and implementing advanced RAG systems. You’ll combine technical depth with a strong feel for how AI should work for users.

You’ll join an ambitious and fast-growing team, with the opportunity to shape the product and learn from experienced serial entrepreneurs.

If you're ready to make a significant impact in a growing company with global ambitions, this could be the right opportunity for you.

What you’ll be doing

A non-exhaustive list of features and challenges we could use your help with:

• Using best practices and industry-leading tools and technologies to solve real-life problems with LLM solutions.

• Building and improving agent harnesses, including context management, tool use, and feedback loops, to make our AI more reliable and useful.

• Owning features from understanding the user’s problem through scoping, building, and rollout. You’ll make product and technical trade-offs with input from Product, Design, colleagues, and users.

• Integrating and synthesising contextual data — including CRM data, call recordings, and emails — to enrich the LLM context and provide more accurate and personalised outputs.

• Exploring the data captured by the product to uncover patterns and opportunities, and experimenting with ways to turn them into useful insights and better experiences for users.

• Developing algorithms for multilingual conversational systems.

• Developing and enhancing RAG systems to ensure high-quality and contextually appropriate responses.

• Building evaluations and observability to ensure AI outputs maintain a high standard of quality, accuracy, and relevance.

We believe in shipping fast to gather feedback quickly from customers. We like to keep things simple, so we use services offered by key vendors where they help. You’ll track usage, follow up on feedback and bugs, and keep improving until the feature delivers value.

You’ll report directly to the co-founder & CTO, while working closely with other departments and customers to define feature requirements and make trade-offs that maximise value while minimising complexity.

Job requirements

• We’re looking for someone passionate about LLMs, with at least 5 years of professional software engineering experience.

• You have hands-on experience building and shipping LLM-powered features in a software product.

• You have experience with TypeScript and Node.js.

• You have a feel for AI interaction design: how an AI should behave, communicate uncertainty, and give users the right level of control. You use that judgment to make thoughtful product decisions.

• You’re curious about the data behind the product and the possibilities it opens up. You enjoy exploring patterns, asking new questions, and finding useful applications while staying critical about what the evidence actually supports.

• You're able to break down big initiatives into small tasks, allowing for re-prioritisation as important opportunities arise.

• Personal growth is important to you, and you have the ambition to thrive in a start-up culture.

• We have global ambitions, so fluency in English is a must.