Hi Product Hunt, I'm Jake and I built TrackPin.

"−35%" on Amazon tells you how far today's price is from the crossed-out list price. It doesn't tell you whether the price is good. The morning I wrote this, 84% of the crossed-out prices in our sample were not below what the product normally sells for.

Price trackers don't fix this either: they give you a chart and leave the call to you. TrackPin makes the call, and it ignores the list price. It records every price it sees for 1.4 million amazon.com products and works out each one's normal price: the lowest price level it held for about a week or more of the last 45 days. Then it gives one verdict:

Great price: 20% or more below normal
Good price: 5 to 20% below
Normal price: within 5%
Above normal: more than 5% above

Every verdict shows how much history it rests on. With under 14 days of data it says "Too early to tell" instead of guessing.

A real pair from this week: two Ninja air fryers. The DualZone is $129.99, 27% below its normal $179.95 and the lowest in 138 days. The 5.5 Qt XL shows "−8%" on its listing, yet it's 65% above the $99.99 it normally sells for.

Try it at trackpin.co: paste an amazon.com link, an amzn.to or a.co link, or an ASIN. No account needed.

Also included:

Price-drop alerts: one email when a product reaches a Good or Great price. No account, no newsletter.
Real deals (trackpin.co/deals): only products below their own normal price.
A bookmarklet for desktop browsers, and Share > TrackPin from the Amazon app on Android.
A JSON API with a free plan of 100 requests a day, for deal bots and price trackers.

Black Friday is 10 days away. Paste in something from your list and tell me what TrackPin says. I'm here all day for questions, edge cases and any verdict you disagree with.