Last month, a friend running a small e-commerce store asked me: "How do big companies track competitor prices? I can't afford $500/month tools." I told him I'd build one for free. It took 30 minutes. Here's exactly how I did it — and you can copy this approach for any niche. Full code on GitHub: price-monitoring-free The Problem Price monitoring tools like Prisync ($99-399/mo) or Competera ($1000+/mo) are built for enterprises. Small business owners need something simpler: Track 10-50 products across 3-5 competitor sites Get notified when prices change See price history over time The Architecture (Dead Simple) ┌─────────────┐ ┌──────────────┐ ┌─────────────┐ │ Scheduler │────▶│ Scraper API │────▶│ JSON Store │ │ (cron/n8n) │ │ (sitemap + │ │ (GitHub) │ │ │ │ product │ │ │ └─────────────┘ │ pages) │ └──────┬──────┘ └──────────────┘ │ ┌────▼─────┐ │ Notifier │ │ (webhook) │ └──────────┘ Step 1: Find Product URLs via Sitemap API Most e-commerce sites expose their product URLs in XML sitemaps. Instead of guessing URLs, parse the sitemap: const axios = require('axios'); const parseStringPromise = require('xml2js'); async function getProductUrls(domain) url.includes('/item')); console.log(`Found $urls.length product pages on $domain`); return urls; const products = await getProductUrls('competitor-store.com'); // Found 847 product pages Pro tip: Check robots.txt first — it often links to multiple sitemaps including product-specific ones like /sitemap-products.xml. Step 2: Extract Prices with Structured Data Here's the trick most people miss: e-commerce sites embed prices in JSON-LD structured data for Google. You don't need to parse HTML — just extract the JSON: const cheerio = require('cheerio'); async function getPrice(url) const data: html = await axios.get(url, headers: 'User-Agent': 'Mozilla/5.0 (compatible; PriceBot/1.0)' ); const $ = cheerio.load(html); const jsonLd = $('script[type="application/ld+json"]') .map((_, el) => try return JSON.parse($(el).html()); catch return null; ) .get() .find(d => d['@type'] === 'Product'); if (jsonLd?.offers) return ; return null; Step 3: Store Price History in GitHub (Free) Instead of paying for a database, use GitHub as a free JSON store: const Octokit = require('@octokit/rest'); const octokit = new Octokit( auth: process.env.GITHUB_TOKEN ); async function savePriceData(prices) const date = new Date().toISOString().split('T')[0]; const content = Buffer.from(JSON.stringify(prices, null, 2)).toString('base64'); await octokit.repos.createOrUpdateFileContents( owner: 'your-username', repo: 'price-tracker-data', path: `data/$date.json`, message: `Price snapshot $date`, content ); Step 4: Detect Changes & Notify async function detectChanges(today, yesterday) const changes = []; for (const product of today) const prev = yesterday.find(p => p.url === product.url); if (prev && prev.price !== product.price) const change = ((product.price - prev.price) / prev.price * 100).toFixed(1); changes.push( name: product.name, oldPrice: prev.price, newPrice: product.price, change: `$change%`, url: product.url ); if (changes.length > 0) await axios.post(process.env.WEBHOOK_URL, content: `Price changes detected!\n` + changes.map(c => `$c.name: $$c.oldPrice -> $$c.newPrice ($c.change)`).join('\n') ); return changes; Step 5: Automate with Cron const competitors = ['store-a.com', 'store-b.com', 'store-c.com']; async function run() const allPrices = []; for (const domain of competitors) const urls = await getProductUrls(domain); for (const url of urls.slice(0, 50)) const price = await getPrice(url); if (price) allPrices.push(price); await new Promise(r => setTimeout(r, 1000)); console.log(`Tracked $allPrices.length products`); await savePriceData(allPrices); run(); Add to cront