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Dylan Ferrara
Dylan Ferrara

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I built a bookmarklet that calls out fake was-prices (build log)

#webdev #tutorial #javascript #ai

The 83% stat needed a weapon, not just a blog post. So I built a bookmarklet: click it on any product page and it shows Fazy's verdict on the price from recorded history.

Why a bookmarklet and not an extension: zero install friction, zero store fees, zero review queue. It's a snippet of JavaScript the user saves as a bookmark. Click on any product page, and it:

  1. Extracts the product name from the page's metadata.
  2. Queries Fazy's free no-key API: https://fazy.com/api/v1/deals/search?q=
  3. Shows the verdict: verified discount vs. claimed, lowest recorded price, dated facts.

Core snippet:

javascript:(async()=>{
  const q = document.querySelector('meta[property="og:title"]')?.content || document.title;
  const r = await fetch('https://fazy.com/api/v1/deals/search?q='+encodeURIComponent(q)+'&limit=3',
    {headers:{'X-Fazy-Agent':'bookmarklet'}}).then(r=>r.json());
  const d = r.data[0];
  alert(d ? `${d.title}\n${d.price.amount/100} (${d.discount_pct}% off, verified)\nLowest recorded: see fazy.com`
          : 'No price history found for this product yet.');
})();
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It's a demo-grade 20 lines, but the pattern is the product: price history as the verdict layer for the entire web.

Full API + MCP docs: https://fazy.com/developers. I built Fazy; the bookmarklet is free and the API is keyless.

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