Founding Engineer; Full Stack​/Backend

Affinity Labs:
Founding Engineer (Backend)

Location: London Area, United Kingdom
· On-site

At Affinity Labs, we’re building the future of company creation, a full-stack AI venture studio that partners with content creators to co-found authentic, scalable software businesses. By combining AI-native development with creator-led distribution, we're pioneering a new model of monetisation by to rapidly build, launch, and scale digital ventures aligned with creators and their audiences.

We aim to launch ventures 10x faster and cheaper than traditional methods using our internal "AI factory": a multi-agent architecture, reusable component libraries, and a growing knowledge graph that learns from every product we ship.

Ship at rapid pace with AI-accelerated workflows, see your work distributed to thousands of users at launch, and compound impact across multiple product, not just one.

You’ll lead end-to-end backend development across our products: scoping services, designing data models and APIs, building, testing, shipping, and iterating in tight cycles. This is an early-stage, hands-on role with significant autonomy and responsibility to drive backend product development, collaborating closely with founders, creators, and product/design to turn lean specs into reliable, scalable services.

• Implement features end-to-end on the backend (APIs → data models → integrations) and maintain quality while moving fast.
• Run tight build, test, iterate, ship loops; provide realistic estimates and surface blockers early.
• Manage tech debt pragmatically
  ; record key decisions as lightweight ADRs/notes in the tooling.
• Participate in daily standups and weekly planning
  , contribute to technical strategy & execute from Linear tickets.
• Contribute to architecture and product discussions; be heard in debate, align to unified decisions.
• Own operability: set up and maintain CI/CD, monitoring/alerting, performance & error budgets, and safe rollback paths.
• Build and integrate AI features (LLM/agent workflows, RAG/vector DB integration, eval hooks, cost/safety guardrails).

• 3-6+ years building production backends/services
  , with shipped work and clear ownership.
• Strong Python (FastAPI) and database skills (
  Postgre
  
  SQL/MongoDB
  ); solid API design fundamentals.
• Familiarity with AWS serverless patterns and Docker for bespoke services; basic CI/CD concepts.
• Comfortable with Redis (caching/sessions) and common queue/messaging patterns.
• Startup mindset: high ownership, pace, ambiguity; willing to burn the midnight oil when needed
  .
• Growth mindset & flexibility: open to feedback; not rigid about stack/tools.
• Clear communicator & collaborator; lean on your experience to guide product decisions.
• Evidence of shipping quickly in small teams (links to repos, case studies, or live services).

• Node.js alongside Python for services or integrations.
• Experience with vector databases (e.g., Chroma) and embedding pipelines.
• Lang Chain or CrewAI for orchestration;
  MCP servers for integrations.
• Security hygiene (secrets, permissions, least-privilege) and practical data-privacy basics.
• Planning & execution in Linear (or similar).

• Backend/Runtime: Python (FastAPI), Node.js.
• Data stores: Postgre
  
  SQL, Mongo
  
  DB (as appropriate), Redis (caching/sessions).
• Vectors/Embeddings: Chroma (or similar).
• AI Models & APIs: Claude (Anthropic), Gemini (Google);
  Amazon Nova Canvas (vision), Deepgram (audio).
• AI Dev Tools: Lang Chain or CrewAI (orchestration), MCP servers (integration), Git Hub Copilot / Claude Code.
• Infrastructure: AWS (serverless functions), Docker (primarily for custom MCPs).
• Frontend (when needed): React/Next.js (for dashboards/admins, used selectively).

• Communicates clearly with technical and non-technical teammates.
• Takes ownership from concept to deploy and through maintenance.
• Balances technical excellence with pragmatic delivery to meet business needs.
• Adapts quickly to changing requirements and emerging tech; applies AI learnings.
• Sets clear goals, tracks progress, and hits commitments; collaborates across disciplines.