Full stack Engineer - AI

Ironwood Digital 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 Ironwood Digital can accelerate your career so you can shape the future. Senior Full-Stack Engineer — Flow (AI Agent Platform) Location: London Victoria Office Work Pattern: Hybrid (4 days office, 1 day remote) Team: Flow (Core AI Infrastructure) About the Role Flow is our internal AI agent platform. This isn't a basic chatbot bolted onto a help center; it is core agentic infrastructure that reaches across our data warehouse, services, and central systems to execute complex work on behalf of the business. Flow powers both internal and client-facing workflows, delivering true automation and replacing traditional ticketing queues with instant, intelligent actions. We are looking for a Senior Full-Stack Engineer to help us transition Flow from a fast-moving internal product to durable, productionized platform infrastructure. You will own complex features end-to-end—including agent workflows, reasoning UIs, and cross-system integrations—while raising the engineering bar and shaping the technical direction of a small, autonomous team. This role sits at the intersection of agentic AI and live operational workflows within a regulated fintech environment. The surface area is the entire company, and your impact will be visible within weeks. What You'll Do Build Action-Oriented Agent Workflows: Design multi-step orchestration, tool use, and retrieval grounded in our data stores using the Strands Agents SDK. Architect End-to-End Features: Own development across a React/TypeScript frontend and Python/FastAPI backend, balancing rapid iteration with platform maintainability. Own the Reasoning Layer: Extend our Chain-of-Thought UI to ensure explainability. In a regulated environment, showing why an agent made a decision is a core feature, not a nicety. Make Agents Measurably Reliable: Build and extend our evaluation harness ( Ragas ) and observability platform ( Langfuse , with session continuity) so we ship changes based on evidence, not vibes. Define Evaluation Strategies: Build custom evaluators, datasets, benchmarks, and automated regression suites to catch quality regressions before they hit production. Integrate Systems & Clouds: Connect internal APIs, data warehouses, email, and cross-cloud GCP/AWS services with robust error handling and distributed tracing. Industrialize Prototypes: Drive the discover → industrialize → productionize lifecycle, turning promising AI prototypes into hardened, daily-deployed services on CD pipelines. Mentor & Lead: Uplift mid-level engineers through code reviews, pair programming, and establishing scalable engineering patterns. Collaborate Cross-Functionally: Partner with Product, Ops, Trading, and Treasury to identify high-value workflows worth automating (and ruthlessly deprioritize the ones that aren't). The Tech Stack Frontend React, TypeScript Micro-frontend architecture Chain-of-Thought / Agent-reasoning UI Vite, Vitest Backend & AI Python, FastAPI Strands Agents SDK (Agent Orchestration) AWS Bedrock RAG / Advanced Retrieval Ragas (Evaluation), Langfuse (LLM Observability) Infrastructure AWS (ECS Fargate, Lambda, API Gateway, S3) with cross-cloud GCP integration Terraform, GitHub Actions Docker Event-driven integration patterns What We're Looking For Must-Haves 5+ years of professional software engineering experience. Strong Python Backend Expertise: Deep experience with FastAPI (or Django/Flask), asynchronous programming, clean architecture, and writing production-grade code. Strong React & TypeScript Skills: Ability to architect non-trivial frontends with sound state management, performance optimization, and comprehensive testing. System Design Judgment: A proven track record of designing scalable, maintainable systems and clearly articulating architectural trade-offs. API & Integration Skills: Proficiency with REST, streaming ( SSE/WebSockets ), and the real-world complexities of stitching together messy upstream systems. Data Proficiency: Strong SQL/NoSQL skills, query optimization, and data modeling. Testing & Ownership Mindset: You treat testing as a core part of the development lifecycle and proactively drive features from ambiguous ideas to production. Excellent Communication: Ability to explain technical decisions to both engineers and non-technical stakeholders, alongside a passion for writing useful documentation. Nice-to-Haves Agentic AI Experience: Hands-on experience with agent orchestration (Strands, LangGraph, AutoGen, or similar), RAG, tool use, and context engineering. Production LLM Systems: Familiarity with LLM observability (Langfuse), evaluation (Ragas), token/cost management, and reliability patterns. AWS Depth: Experience with Lambda, ECS, Bedrock, or equivalent cloud services (cross-cloud exposure is a major plus). Event-Driven Architectures: Experience with event streaming and message brokers. Regulated Environments: Experience working within fintech, compliance, or similar sectors with strict data-residency and auditability constraints. Micro-frontends & IaC: Experience with micro-frontend architecture and Infrastructure as Code (Terraform/CDK). #LI-JB1 About us Ironwood Digital 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, Ironwood Digital 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 Ironwood Digital 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 Ironwood Digital, you can be whoever you want to be and still feel a sense of belonging no matter your story.