MarginCanary

Track your dropshipping supplier's product pages and get an email alert the moment the price changes, a product goes out of stock, comes back in stock, or your profit margin drops below a threshold you set (enter what you sell the product for, and MarginCanary alerts you when a supplier price hike eats into your margin — not just when the raw price moves).

If you have zero coding experience, start with DEPLOYMENT_GUIDE.md — it walks through getting this live on the internet for free, step by step, using only web dashboards (no software to install, no command line).

What's in this project

• app/ — the website itself (Next.js: landing page, login/signup, dashboard)
• components/ — reusable UI pieces (product card, add-product form, chart)
• lib/ — the actual logic: the scraper, the email sender, the Supabase database connections
• supabase/schema.sql — the database structure, run this once in Supabase
• supabase/schema-margin.sql — adds sell price + margin alert threshold, run this once too (after schema.sql)
• supabase/schema-billing.sql — adds each user's plan and Stripe IDs; run this once after schema-margin.sql
• supabase/schema-checks.sql — adds shipping and fees per sale, tracks when each product was last checked, and limits which columns users can edit; run this once after the other schema files
• supabase/schema-security.sql — makes the database enforce the plan limit and the alert recipient, and keeps check results server-only; run this last (safe to re-run)
• .github/workflows/cron.yml — the free scheduler that checks all products automatically every 6 hours

Stack (100% free tier)

Piece	Tool	Free tier
Hosting	Vercel	Yes, generous Hobby plan
Database + auth	Supabase	Yes, 500MB DB
Email alerts	Resend	Yes, 3,000 emails/month
Scheduler	GitHub Actions	Yes, free for personal repos

Local development (optional — only if you later want to code)

npm install
cp .env.example .env.local   # fill in your real keys
npm run dev