Full Stack Engineer

About H6
H6 builds governed AI automation for finance teams. We combine AI with clear business controls, auditability, and human oversight to automate operational workflows without replacing the systems customers already use. Our software runs in production for real customers every day. We are a small, senior team that ships continuously and works closely with customers.
The role
You will work across our backend services, integrations, data layer, and web application. You will design APIs and data models, build integrations with external business systems, contribute to AI-assisted features, and develop the interfaces users rely on to configure and review automation. You will own features end-to-end, from design through implementation, testing, review, deployment, and production support.
What you’ll do

• Design and build APIs and business logic in Python using FastAPI, SQLAlchemy, and Pydantic
• Evolve a multi-tenant PostgreSQL data model, including schema design, migrations, performance, and data isolation
• Integrate with third-party finance and business platforms
• Handle authentication, retries, idempotency, reconciliation, and partial failures
• Contribute to AI-assisted features using LLMs and structured outputs
• Build reliable controls, evidence, and review workflows around AI-generated outcomes
• Build and ship frontend features in React and TypeScript
• Debug issues across the full processing path
• Write automated tests and ship through peer-reviewed pull requests and CI/CD
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What we’re looking for
Must have

• At least four years of experience building production web applications
• Strong Python backend engineering skills
• Solid PostgreSQL experience, including schema design, migrations, and query performance
• Experience integrating third-party APIs where documentation and external data are imperfect
• Practical React and TypeScript experience
• A good understanding of reliability concerns such as retries, concurrency, and failure recovery
• A bias toward small, reviewable changes and root-cause fixes
• The ability to translate complex business requirements into maintainable software

Nice to have

• Hands-on experience with LLM APIs, structured extraction, prompt design, embeddings, or AI evaluation
• Experience combining probabilistic AI with deterministic business controls
• Familiarity with explainability, auditability, or human-in-the-loop systems
• Experience in finance, accounting, procurement, or another data-heavy business domain
• Browser or desktop automation experience
• Experience with Azure, Docker, queues, and automated CI/CD

How we work

• Small team, high ownership
• Production reliability over prototypes
• All changes go through meaningful review and automated checks
• We document important decisions and operational constraints
• AI tooling is part of how we build, but engineering judgement remains essential
  

Sound like you? We’d love to hear from you. Please send us your CV together with a short note introducing yourself and outlining any relevant experience. Where possible, include an example of a project, integration, or production system you have worked on and the role you played in delivering it.