30 - Partime Senior Full-Stack Engineer — Next.js / Supabase / Multi-tenant SaaS

About the role

We're looking for a senior full-stack engineer to join a project build on a part-time basis: a multi-tenant B2B SaaS platform that brings structured workflows to a collaboration process currently managed through scattered tools and manual back-and-forth.

A fully interactive HTML prototype already exists, and a lead developer will own the technical architecture. You'll work alongside them throughout the project — the first phase is spent aligning together on the architecture and implementation plan before any development starts, so you'll help shape the technical direction rather than just execute it.

This is a genuinely complex build — 20+ screens, interconnected modal state, a 10+ table relational schema, AI-assisted validation logic, and regulatory compliance requirements baked into the core logic.

What you'll work on

• The Next.js/React/TypeScript application, in close collaboration with the lead developer

• A multi-tenant Postgres schema with row-level security

• Core business logic including rule-based gating, usage caps, AI-driven validation, and magic-link auth

• Centralised state for a real-time board with modals and filters

• AI text and vision integrations

• Dual-channel notifications, drag-and-drop, real-time updates, calendar view, and GDPR erasure flows

Who we're looking for

A broad, solid senior full-stack profile — you don't need to be the deepest specialist in every area, but you need to hold your own across the whole stack and contribute meaningfully to architecture discussions:

• Solid production experience with Next.js (App Router), React 18, and TypeScript (strict mode)

• Strong PostgreSQL skills, with a working understanding of multi-tenant architecture and row-level security — you should be able to reason about tenancy and policy design, even if you haven't been the primary owner

• Experience with Supabase (or equivalent) and modern client state management (Zustand, React Query, or similar)

• Comfortable collaborating closely with a lead developer: reviewing and being reviewed, discussing trade-offs, and aligning on an implementation plan before writing code

• Reliable part-time availability for the full project duration

Nice to have

• Real-time features (Supabase Realtime, WebSockets, or equivalent)

• LLM API integration (text or vision)

• Background job systems (Inngest/Trigger.dev)

• B2B SaaS RBAC experience

• GDPR operational know-how (erasure, retention, anonymisation)

Stack

Next.js 14+ · React 18 · TypeScript (strict) · Tailwind + shadcn/ui · Zustand + React Query · PostgreSQL (Supabase/Neon) · Clerk/Supabase Auth · Resend/Postmark · Inngest/Trigger.dev · OpenAI/Claude (text + vision)