Senior Fullstack Product Engineer (AI Accounting Platform) - Part-time - EU

About the role

We’re looking for a senior engineer to build and ship production SaaS features at the intersection of AI, accounting, and compliance-heavy systems. You’ll own features end-to-end across backend, frontend, and AI-driven document workflows.

Required Experience

• 5+ years building production SaaS systems
• Experience shipping financial, healthcare, or compliance-heavy software
• Production experience with AI / LLM-powered features
• Designed multi-role permission systems (RBAC)
• Worked with background jobs, queues, and real-time updates
• Comfortable owning features end-to-end (not just tickets)

Technical Skills

Backend

• Node.js (TypeScript) or Python (FastAPI / Django)
• PostgreSQL (schema design, migrations, indexing)
• Background jobs / queues (BullMQ, Celery, Sidekiq, or similar)
• Webhooks (Stripe, GoCardless, or similar)
• REST API design and validation
• Security: JWT/session auth, RBAC, audit logging

Frontend

• React (or equivalent SPA)
• Complex UI workflows (bulk actions, modals, previews, role-based UI)
• State management (React Query, Zustand, Redux, or similar)
• Real-time updates (WebSockets / Socket.IO)

AI & Document Processing

• Anthropic Claude and/or OpenAI APIs
• Structured JSON prompting and validation
• Cost, latency, and retry management
• OCR / PDF / image ingestion (Textract, Tesseract, or similar)

Technologies You’ll Use

• Languages: TypeScript (preferred), Python, SQL
• Frontend: React, HTML/CSS, MUI / Chakra / Tailwind
• Backend: Node.js (NestJS / Express) or Python, PostgreSQL, Redis
• AI: Claude / OpenAI, OCR tools, Zod or Pydantic
• Infra: Docker, CI/CD, S3 or equivalent, WebSockets

Nice to Have

• UK accounting or VAT knowledge
• Subscription billing systems
• PostgreSQL full-text search (FTS / pg_trgm)
• SaaS experience in accounting, fintech, or legal domains