Mid-Full-Stack Engineer - AI Agent Platform

Halcyon Labs helps ambitious businesses unlock global growth, and we take the same approach with our people. We encourage innovation and movement, collaboration and problem-solving, and foster an environment where everyone can feel they belong, are valued, supported and empowered to succeed. If you’re a collaborator who wants to help transform how businesses operate globally, get in touch - we’d love to discuss how Halcyon Labs can accelerate your career so you can shape the future. Mid-Full-Stack Engineer - AI Agent Platform London Victoria Office - Hybrid: 4 days in the office, 1 day working from home About the Role We're building an AI-powered financial crime investigation platform that's transforming how Halcyon Labs's compliance teams work. Our AI agents will process thousands of screening cases, reducing analyst workload while maintaining regulatory standards. We're looking for a Mid Full-Stack Engineer to join our growing team. You'll work across the entire stack - from React frontends to Python backends to LLM integrations - shipping features that directly impact compliance operations. This is a unique opportunity to work at the intersection of AI/ML, fintech, and compliance - building production AI systems that handle real financial crime investigations. What You'll Do Build end-to-end features across our React frontend and FastAPI backend Develop AI agent workflows using LangGraph for screening automation and m ore Integrate with multiple data sources (internal APIs, third-party services, data warehouse) Improve the user experience for compliance analysts using our platform daily Write clean, tested code with good documentation Collaborate closely with Product, Design, and Compliance stakeholders Learn and grow - we'll help you develop expertise in AI/LLM systems Tech Stack Frontend : React 19, TypeScript, Material-UI Module Federation (Micro-frontend architecture) Vite, Vitest Backend : Python 3.13, FastAPI LangGraph (AI agent orchestration) AWS Bedrock DynamoDB, OpenSearch Infrastructure : AWS (ECS Fargate, Lambda, API Gateway) Terraform, GitHub Actions Docker, Kubernetes What We're Looking For Must Have: 2- 5 years of professional software engineering experience React + TypeScript experience (or strong frontend skills with willingness to learn) Python backend experience (FastAPI, Django, or Flask) Solid understanding of REST APIs and async programming Comfortable with SQL databases and NoSQL (DynamoDB, MongoDB) Good testing practices (unit tests, integration tests) Clear communication skills - you can explain technical concepts to non-engineers Curiosity about AI/LLM - you're excited to learn, even if you haven't worked with it before Nice to Have: Experience with LLMs/AI (OpenAI, Claude, LangChain, etc.) Knowledge of AWS services (Lambda, ECS, DynamoDB) Familiarity with streaming (SSE, WebSockets) Previous work in fintech, compliance, or regulated industries Experience with micro-frontend architectures Why Join Us? Greenfield AI Product : You'll help shape a product from early stages, not maintain legacy code. Your architectural decisions will have lasting impact. Technical Leadership : Drive technical direction for a growing team. Mentor engineers and establish patterns that scale. Cutting-Edge A I: Work with the latest LLM technologies in production - LangGraph, RAG, multi-agent systems, and more. Real Impact : Our AI agents process thousands of compliance cases. You'll see your work making a difference within weeks. Startup-within-Enterprise : Small, autonomous team with startup speed, backed by enterprise resources and stability. About us Halcyon Labs delivers sophisticated, integrated solutions — business accounts, hedging, and financing — on a single platform with a seamless workflow. Our success is built on a simple premise and singular purpose: To help businesses operate and scale globally. Since its founding in 2009, Halcyon Labs has always been a fast-growing leader in fintech. Today, we bring together 1,800+ Eburians across nearly 70 cities and we’re always looking to add to our team. At the heart of our offering is a proprietary platform, purpose-built to help businesses seamlessly streamline and manage global cash flow. We focus on continuous product evolution and innovation to build the infrastructure for borderless growth and help our clients scale at every stage. The opportunities at Halcyon Labs are as diverse as our people, ranging from business development to engineering roles across our tech pillars. We believe in inclusion. We stand against discrimination in all forms and are against the intolerance of differences that makes us a modern and successful organisation. At Halcyon Labs, you can be whoever you want to be and still feel a sense of belonging no matter your story.