Senior Engineer to Own a Two-Sided Marketplace Build — Next.js + Supabase + Stripe |

You'd own the architecture, not work the tickets. If that's not what you're looking for, this isn't the role. Overview We're building ConstructionTrader — a mobile-first marketplace where construction companies post surplus materials, idle equipment, available crews, hauling capacity, and yard space. One board, thirteen categories, free to post, with an offering/looking-for and for-sale/for-rent/open-to-trade facet across the whole thing. Launch market is Calgary, AB, single-metro by design. Think classifieds with real trust infrastructure, built for someone standing in a yard on a phone with two bars of signal and gloves on. That's the actual UX bar — not visual polish. This is not a website project. It's an MVP with a defined liquidity goal, and the person we hire needs to think that way. What we mean by "own it" This is the part that matters most, so read it before you apply. We are not looking for someone to implement a spec. We're looking for someone who takes an outcome — "a contractor can post a surplus load in under 30 seconds and get a qualified reply" — and comes back with a plan, a schema, and a list of the three things they'd cut. Concretely, you own: The architecture and the data model. Category taxonomy into a schema that holds up when we add categories 14 and 15. The security posture. Row-level security on every table. Authorization checked on every route, not just authentication. You write the access-control test before the feature. The quality gates. Stripe webhooks as source of truth with signature verification and idempotency. File uploads validated by magic bytes, size-capped server-side, EXIF stripped. Consent captured and timestamped per channel from the first migration (CASL/CAN-SPAM). Deployment, environments, and monitoring. Staging that isn't pointed at production. The handover. Documentation good enough that a second engineer is productive in a day. If you leave, we should not be stranded. Saying no. If we ask for something that will cost three weeks and win nothing, we expect to hear that before you build it, not after. You will not be micromanaged. You will be held to what you committed to. Not married to this but here is a sense: Stack (chosen — not up for a rewrite) Next.js (App Router) + TypeScript Supabase — Postgres, Auth, Storage, RLS Stripe Checkout (we are the merchant; no Connect, no escrow, no payouts) Resend (transactional email), Twilio (SMS alerts) Vercel, GitHub, PostHog or equivalent from day one Boring and well-documented is deliberate. If you want to argue for one substitution, make the case in your proposal — but "I'd rather use [my framework]" ends the conversation. Send me a spec or approach and. I Look forward to hearing from you.