Senior Full-Stack Engineer — Multi-Tenant SaaS & AI Integrations (WW-PT)

Role Overview

We are seeking an experienced Senior Full-Stack Engineer to join our team in developing a cutting-edge multi-tenant SaaS platform tailored for local service businesses. This role demands a high level of technical expertise, strategic thinking, and the ability to work within and improve upon an existing architecture. Your primary focus will be on assessing, architecting, and building robust solutions that integrate seamlessly with multiple AI providers, ensuring the platform's scalability and security.

Responsibilities

• Conduct a comprehensive review of the existing codebase and architecture to identify technical risks, gaps, and potential improvements.
• Architect and develop production-ready features for a multi-tenant SaaS platform, ensuring scalability and security.
• Implement secure tenant isolation using PostgreSQL Row-Level Security (RLS).
• Develop backend and application functionality using Node.js and TypeScript.
• Manage serverless infrastructure and deployments on Vercel.
• Integrate various AI providers, including OpenAI, Anthropic, and Azure OpenAI, into the platform.
• Design provider-abstraction layers to allow flexibility in AI provider or model selection without tight coupling.
• Develop practical automation and agent-based workflows utilizing LLMs and external services.
• Proactively identify architectural risks, scalability concerns, and security issues.
• Create secure integrations and webhook-driven workflows as needed.
• Oversee the code review process, automated testing, and deployment to production environments.
• Communicate progress and technical decisions effectively to both technical and non-technical stakeholders.

Required Skills

• Proven experience in architecting a production multi-tenant SaaS system independently.
• Expertise in Node.js and TypeScript.
• In-depth knowledge of PostgreSQL, specifically implementing Row-Level Security (RLS).
• Experience with serverless architecture deployments, particularly on Vercel.
• Demonstrated experience integrating multiple AI/LLM providers, such as OpenAI, Anthropic, or Azure OpenAI.
• Skill in building provider-abstraction layers or similar architectures.
• Practical experience in developing AI-powered automation, agent workflows, or multi-step LLM workflows.
• Strong architectural judgment and the ability to identify risks, edge cases, and tradeoffs.
• Capability to work independently at a senior level with minimal oversight.

Nice to Have

• Experience with conversational or voice AI platforms like Retell, Vapi, Bland, or similar.
• Proficiency in building webhook-heavy or event-driven systems, including signature verification and idempotent processing.
• Familiarity with modern frontend frameworks such as React or Next.js.
• Experience guiding early-stage SaaS products from prototype to production.
• Knowledge of AI observability, model routing, fallback strategies, cost management, and reliability patterns.