AI Engineer (LLM & Agents) in London

Ecommpay is on a mission to build a global, data‐driven payment ecosystem. We help top e‐commerce companies grow globally with local bespoke solutions. You have a unique chance to be the driving force behind Ecommpay's AI capabilities as a Founding AI Engineer. We're looking for a builder who's equally comfortable prototyping a new agent architecture and deploying it to production. If you've been tinkering with LLMs, building RAG pipelines, and dreaming about what AI can do for fintech—this is your chance to make it real.

Responsibilities

• Design, build, and maintain LLM‐based applications and agentic systems that solve real business problems across the organization.
• Develop and optimize RAG pipelines for internal knowledge retrieval, document processing, and multilingual content.
• Build and deploy AI agents capable of autonomous task execution, tool use, and multi‐step reasoning.
• Integrate LLM capabilities with existing systems via APIs and MCP (Model Context Protocol), working with payment platform data and business workflows.
• Evaluate, fine‐tune, and benchmark models for specific use cases (cost, latency, accuracy trade‐offs).
• Maintain and extend our AI platform infrastructure (Open‐source web based user interfaces, AWS Bedrock, embedding models, vector databases).
• Collaborate with business stakeholders to identify high‐impact AI opportunities and translate them into working solutions.
• Stay current with the rapidly evolving LLM/agent landscape and bring relevant innovations into our stack.

Requirements

• 3+ years of software engineering experience, with at least 1 year focused on LLM applications.
• Hands‐on experience building with LLM APIs (OpenAI, Anthropic Claude, AWS Bedrock, or similar).
• Practical experience implementing RAG systems: embeddings, vector stores, retrieval strategies, chunking approaches.
• Familiarity with agent frameworks and patterns (function calling, tool use, ReAct, multi‐agent systems).
• Strong Python skills; comfortable with async programming, API development, and data pipelines.
• Experience with cloud infrastructure (AWS preferred: Lambda, ECS, Bedrock, S3).
• Understanding of prompt engineering principles and LLM evaluation methodologies.
• Self‐directed problem solver who thrives with autonomy and minimal hand‐holding.
• Fluent English (written and spoken).

Nice to have

• Experience with LangChain, LlamaIndex, or similar orchestration tools.
• Background in payments, fintech, or e‐commerce domains.
• Experience with Kubernetes and containerized deployments.
• Familiarity with fine‐tuning or training models (LoRA, PEFT, etc.).
• Knowledge of compliance/security considerations for AI in regulated industries.

What we offer

• Make your mark on a fast‐growing fintech industry becoming part of 500+ team with 4 offices worldwide.
• Enhance your skills with our own Academy and receive compensation for additional trainings and courses to foster your growth.
• Earn performance‐based bonuses tied to achieved KPIs.
• Accumulate your Loyalty Days as a reward for your years of commitment.
• Get an extra paid day off to celebrate your birthday.
• Enjoy the flexibility of a hybrid work model.
• Receive generous health insurance including dental, 5 Health Leave days per year and access to a private gym in the office.