Full Stack Engineer - Marketplace Infrastructure

Quick Facts

• Company: ConstructionYardSale.com (CYS)
• Role: 1 of 2 Full Stack Engineers - Infrastructure & Integrations
• Compensation: Equity only to start
• Location: Remote (US)
• Commitment: Part-time to start, move to full-time upon company growing
• Target start: ASAP

About ConstructionYardSale.com

ConstructionYardSale.com is a verified peer-to-peer marketplace for buying and selling used, surplus, and overstock construction materials and equipment - built for contractors, HVAC and electrical trade professionals, builders, remodelers, and DIY homeowners. We're launching first in Hartford County, Connecticut, with New England expansion planned for later this year.

Every transaction is local pickup only - no freight, no shipping to manage. Payments are protected by a pickup-code release/verfication system: the buyer generates a release code and hands it to the seller at pickup, which triggers payment capture and payout. Simple on the surface but behind it sits a real, interconnected system: a custom API layer on top of a hosted marketplace platform, a marketplace payments architecture on Stripe Connect, event-driven automations in Supabase, and a full notification, monitoring, and security stack around all of it.

We're a small, founder-led team, pre-launch and pre-institutional-funding. There's no cash compensation on this role right now. What's on offer is real ownership of a live product handling real transactions from day one.

The Full Stack

This is the complete picture of what you'd be stepping into. You will need some expertise in most tools on day one, and you should be excited to become the person who understands how all of it connects and works.

Core platform & backend

• Sharetribe (hosted marketplace platform) - listings, search, messaging, transactions
• Custom BFF (Backend-for-Frontend) layer - Node.js, ~60 private API endpoints sitting between the frontend and Sharetribe, enforcing our business logic (seller tiers, permissions, fee rules, verification gating)
• Supabase - Postgres database, authentication (passwords, resets, OTP), and event-driven edge functions
• React / Tailwind - our marketing and coming-soon site

Payments & money movement

• Stripe Connect (destination charges) - CYS as merchant of record; pre-authorization at checkout, capture triggered at pickup-code verification, timed auto-capture fallback, refunds and reverse transfers
• Stripe Tax API - automated sales tax calculation on both the item sale and the marketplace fee
• ACH Direct Debit - used for higher-value transactions to control processing costs
• Stripe verification - identity verification gating for paid seller tiers
• Mercury - banking and payout destination

Automations (Supabase event-driven functions)

• Pickup-code generation and verification
• Listing boost scheduling and expiration
• Review averaging
• AI-assisted listing moderation
• Notification triggers

Communications & notifications

• Twilio - SMS and OTP, including A2P 10DLC registered campaigns (login verification and pickup-code notifications)
• Postmark - authentication emails (via Supabase)
• Courier - transactional notification templates and routing
• SendGrid - Sharetribe outbound marketplace email
• Mailchimp - marketing email and waitlist (owned by our marketing team, but you'll touch the integration points)

DevOps, monitoring & security

• GitHub - all code lives in private repositories, including the BFF server, the coming-soon/marketing site, and our Supabase functions (placeholder — confirm exact repo list before posting)
• Render - backend and site hosting/deployment
• Sentry - error monitoring and alerting across the stack
• Cloudflare Zero Trust - access control and security in front of internal surfaces
• Replit - dev environment

Data, accounting & operations

• QuickBooks Online + Stripe Sync (Acodei) - automated posting of Stripe activity to the ledger, including sales tax mapping
• Plausible - site analytics
• Freshdesk - helpdesk/ticketing (you'd be the escalation point for anything technical)
• Zapier / Make - lightweight automation glue between tools
• How It All Fits Together

The reason we're listing everything is that this role isn't about any one tool, it's about the seams between them. A single transaction touches nearly the whole stack:

A user signs up → Supabase handles auth and OTP (SMS via Twilio Verify, emails via Postmark), and a linked Sharetribe account is created behind the scenes. They list an item → the listing flows through the BFF layer, gets screened by our AI moderation function, and can be boosted via a Stripe purchase. A buyer checks out → Stripe Connect places a destination-charge pre-authorization, and Stripe Tax runs calculations on both the item and our fee. A Supabase function generates the buyer's pickup code. At pickup, the buyer hands the seller the code → verification triggers payment capture, the seller's payout routes toward Mercury, and Courier and Twilio fire the confirmation notifications. Reviews post and get averaged by another Supabase function. Acodei syncs the whole transaction into QuickBooks, Plausible tracks the funnel, Sentry tells us if anything broke along the way, and Cloudflare Zero Trust keeps the internal surfaces locked down.

If reading that paragraph makes you want to open the repos and see how it's wired - this is your role.

About the Role

Our current infrastructure contractor is wrapping up his engagement around launch, and we need someone to take over everything above and work with our second founding Engineer. There will be two of you, but you will take on a lot of responsibility. Picture this as a hybrid role: hands-on implementation work - building endpoints, fixing bugs, shipping changes - combined with full architectural ownership of the system, and more dedicated day-to-day attention than any prior contributor has given it.

You'd be one of a very small number of people who understand how the whole system fits together. That means real autonomy over technical decisions, direct input on what gets built next, and no bureaucracy between you and shipping.

What You'd Own

• The BFF layer - maintain the ~60 existing endpoints and build what's needed next, including tier permissions and fee logic
• The full Stripe integration - destination charges, pre-auth/capture flow, Stripe Tax calculations, refunds and reverse transfers, ACH, verification, and payout monitoring
• Auth - the Supabase authentication system and its sync with Sharetribe accounts
• Pickup-code escrow - the logic protecting every transaction between payment and confirmed pickup
• All Supabase automations - moderation, boosts, reviews, notifications, pickup codes — plus whatever we need to build next
• The notification stack - Twilio, Postmark, Courier, and SendGrid, kept running and compliant (including A2P 10DLC)
• DevOps & reliability - GitHub repos, Render deployments, Sentry triage, and Cloudflare Zero Trust administration
• Production support - you'll often be the first, and sometimes only, line of technical response when something breaks
• Turning business needs into working software - you'll work directly with our non-technical CEO, so explaining tradeoffs in plain English matters as much as the code itself
• Scaling ahead - preparing the stack for multi-state expansion, targeted for Q4 2027

What We're Looking For

• Strong backend engineering experience, ideally Node.js/JavaScript or TypeScript
• Hands-on experience with Stripe - Stripe Connect or other marketplace/multi-party payment experience is a big plus
• Experience with Supabase, Postgres, or a comparable auth/database platform
• Comfort working across many third-party APIs and making them behave as one system - SMS, email, tax, payments, accounting
• Comfort working with (or quickly learning) a headless, API-driven platform - direct Sharetribe experience is a strong plus, though rare, so not required
• Familiarity with monitoring and access tooling like Sentry and Cloudflare (Zero Trust a plus)
• A self-directed, ownership-oriented approach - we're a very small team, and you'll be trusted with real decisions from day one
• Prior early-stage or startup experience, and comfort with ambiguity
• Strong communication skills, especially explaining technical tradeoffs to a non-technical founder

Nice to Have

• Experience with two-sided marketplaces, trust & safety, or escrow-style payment flows
• Experience with Stripe Tax or multi-state sales tax automation
• QuickBooks Online integration experience
• Twilio A2P 10DLC / carrier compliance experience
• Background in construction tech, home services, or similar B2B/B2C marketplaces

Compensation
This is an equity-only engagement to start - there's no cash compensation at this stage. Consistent with how we've structured other roles on the team, we're proposing a target ownership stake of 0.5%to 1% of the Company's fully diluted capitalization at time of issuance. The final percentage, vesting schedule, and other equity terms will be set out in a Stock Purchase Agreement once we complete our planned conversion from an LLC to a Delaware C-Corporation. In the meantime, this would begin as an independent contractor engagement covering scope and IP assignment. Happy to talk specifics during the interview process.

How to Apply

Send a short note about your experience with Stripe, Supabase, and/or marketplace platforms — and if the "How It All Fits Together" section above genuinely excited you, say so and tell us why. Links to relevant code or projects are welcome. We're moving quickly ahead of our August 15 launch and would love to talk soon.