Price History Tracker

The problem

The sale price needs a reference you don't have

The EU's Omnibus Directive requires that promotional prices reference the lowest price of the previous 30 days. The FTC's Deceptive Pricing guidelines require that "former prices" reflect genuine bona fide prices. In practice, retailers routinely inflate a product's price for 10-14 days before a sale event, then mark it down with a prominent percentage badge.

The "original" price was never the real price — it was a reference point manufactured specifically to make the sale price look bigger. A European Commission cross-border sweep found that 60% of online retailers were using some form of manipulative pricing practice.

Most consumers have no way to verify whether a discount is genuine without historical price data.

How it works

Step by step

1. Install the extension in Chrome.
2. Browse product pages normally — the extension records prices automatically in the background.
3. On subsequent visits, the extension injects a price history sparkline directly onto the product page, next to the current price.
4. The sparkline shows price movement over the past 90 days, stored locally on your device.
5. A genuine discount shows a clear price drop. A fake discount shows a price that was inflated recently and is now back to its normal level.

Who it's for

What's included

• Full Chrome extension source code (Manifest V3)
• Price extraction for major retail sites
• 90-day local price history storage
• Inline sparkline renderer
• Vanilla JavaScript, no dependencies