Lowballer.org

Know your number before you make the offer. Screenshot any Facebook Marketplace listing or Copart lot — Lowballer pulls live comps, prices the repairs, and hands you the exact lowball offer or max bid to make.

Three modes: Car (market value − repairs = your offer) · Any item (eBay sold comps → flip profit) · Copart/Salvage (rebuild cost → your max bid).

Quick start

1. Install (Node.js 18+):

   npm install
   

2. Configure — copy the env template and fill in your keys:

   cp .env.example .env.local
   

   • ANTHROPIC_API_KEY — from https://console.anthropic.com (powers all appraisals)
   • STRIPE_SECRET_KEY + STRIPE_PRICE_ID — create a recurring $30/month price in https://dashboard.stripe.com, use test keys first
   • STRIPE_WEBHOOK_SECRET — see Stripe webhook (dev) below
   • APP_SECRET — any long random string (openssl rand -hex 32)
   • DATABASE_URL — a Postgres connection string (Neon, Railway, or Vercel Postgres free tiers all work). Also copy it into a plain .env file (Prisma CLI's convention, separate from Next's .env.local) so npx prisma migrate dev works without manually passing it.
   • RESEND_API_KEY + EMAIL_FROM — optional in dev. Without a key, magic-sign-in links print to the server console instead of emailing, so local sign-in still works.
3. Set up the database:

   npx prisma migrate dev --name init
   

4. Run:

   npm run dev
   

   Open http://localhost:3000. There's no free tier: every non-Pro appraisal runs, shows a short preview, and unlocks for $5 (one-time Stripe Checkout). Pro ($30/mo) gets full results.

Stripe webhook (dev)

Subscription status (new subscriptions, cancellations, failed payments) is synced by app/api/stripe/webhook/route.js. To exercise it locally:

stripe listen --forward-to localhost:3000/api/stripe/webhook

This prints a whsec_... value — put it in STRIPE_WEBHOOK_SECRET. Then, in another terminal:

stripe trigger checkout.session.completed
stripe trigger customer.subscription.deleted

In production, add the endpoint in the Stripe dashboard (Developers → Webhooks) pointed at https://<your-domain>/api/stripe/webhook, subscribed to checkout.session.completed, customer.subscription.updated, customer.subscription.deleted, and invoice.payment_failed — then put that endpoint's own signing secret in STRIPE_WEBHOOK_SECRET on the host.

Deploy

Easiest path is Vercel: push this repo to GitHub, import it at https://vercel.com, add the four env vars (set NEXT_PUBLIC_BASE_URL to your live URL), deploy, then point the lowballer.org domain at it. Switch Stripe to live keys when ready.

Working on this with Claude Code

This repo ships with a CLAUDE.md so Claude Code understands the architecture immediately.

npm install -g @anthropic-ai/claude-code
cd lowballer
claude

Then just describe what you want: "add a Stripe webhook for cancellations", "add a history page of past appraisals", "make the hero animate on load". Docs: https://docs.claude.com/en/docs/claude-code/overview

Before real customers (in rough order)

1. Stripe webhook so cancellations actually revoke Pro — done (app/api/stripe/webhook/route.js)
2. Accounts + database so usage/Pro survive cookie clears and work across devices — done (magic-link sign-in, Postgres/Prisma, see BUILD_SPEC.md Phase 2)
3. Rate limit /api/appraise to cap your Anthropic API spend — done (30 requests/15min per IP, 20 metered calls/hour per user — see lib/rateLimit.js)
4. Terms of service + "estimates only" disclaimer page

How it works

• Car mode: upload up to 6 photos/screenshots (compressed in the browser). One server-side call returns a verdict + 0–100 score, market value with real comps, evidence-backed red flags, an itemized repair estimate, flip potential and an inspection checklist — all counted as a single free appraisal. See lib/vehicleAnalysis.js.
• Pasting a Facebook Marketplace link (optional; open to everyone with LINK_SCAN_MODE=all, non-Pro within daily caps): the listing is loaded via ScrapeCreators, then prefilled like a screenshot import. Set SCRAPECREATORS_API_KEY, and LINK_SCAN_MODE / LINK_SCAN_TESTERS to control who sees it — see lib/listingFetch.js.
• The browser never sees your Anthropic key — all AI calls go through app/api/appraise, which calls Claude (claude-sonnet-4-6) with the web search tool and returns parsed JSON.
• Pay per result: non-Pro research calls are stored server-side (lib/lockedResults.js) and only a teaser is returned; /api/unlock starts a $5 Stripe Checkout and the webhook / redirect marks the result paid. The paid details never reach the browser before payment.
• Pro is granted by the Stripe webhook (app/api/stripe/webhook/route.js) syncing subscription status onto your account; app/api/checkout/verify is just a fast-path UI nudge, not the real source of truth.
• Listing screenshots are read by Claude vision (base64 images in the message content) — that's how Facebook Marketplace listings work despite having no API.