Launch announcement
Amazon Price History — see Amazon's true price over time.
A free Manifest V3 extension for amazon.com that drops a sparkline panel into every product page, flags the delta vs. its 90-day low, and tracks how much you would have saved cumulatively across the last year. Browser-local, no account, no remote calls.
What it does
Four things it does on every Amazon product page.
The extension reads what is already on the page, appends one sample to local storage, and renders a compact panel inline beneath the current price — no extra tab, no popup, no account.
90-day sparkline
A compact price history chart rendered directly under the current price block. Hover to see the daily close; the panel appears immediately on second visit and grows visit by visit.
Delta vs. 90-day low
A colour-coded badge next to the header: emerald at-or-near low, amber within ten percent, rose above. Tells you at a glance whether today's price is actually a deal.
Cumulative savings tracker
Every price drop you would have caught is logged; the panel surfaces a running total saved across the last 90 days, per ASIN, surfaced on hover.
Honest affiliate disclosure
Links on Amazon product pages pass through the Amazon Associates program. We earn a small commission at no extra cost to you — the disclosure is rendered directly under the chart panel.
How to install from the Chrome Web Store
Three steps and you are tracking Amazon prices.
The CWS listing goes live alongside this announcement — search for Amazon Price History and click Add to Chrome. No developer mode, no unpacked load.
- 1
Open the Chrome Web Store listing
Click the button below — it opens the Amazon Price History CWS listing in a new tab.
- 2
Click "Add to Chrome"
Chrome shows the permission summary:
storage+activeTab, scoped tohttps://www.amazon.com/*. Approve and the icon lands in your toolbar. - 3
Open any Amazon product detail page
The sparkline + delta badge + savings tracker appear directly beneath the price block on the second visit. Every future visit appends a sample to the local 90-day window.
Affiliate disclosure
Honest from day one.
Extensify participates in the Amazon Services LLC Associates Program — an affiliate advertising program designed to provide a means for sites to earn fees by linking to amazon.com. Affiliate links route through Amazon's standard program; commissions do not change your price. Cumulative savings are calculated against prices you actually saw, not list price.
FAQ
Questions about the launch.
What the extension does, what it does not, and how the affiliate relationship works.
Is Amazon Price History free?
Yes — fully free, no Pro tier, no in-app purchases, no paywall. The extension ships the same feature set to every install; nothing is gated on an account, login, or license key.
Does it work on every Amazon listing?
Amazon.com product detail pages (ASIN pages, e.g. https://www.amazon.com/dp/<ASIN>/) today. host_permissions is pinned to https://www.amazon.com/* by design; variant pages that lack a price element, search result pages, and non-product URLs are left untouched. amazon.co.uk, amazon.de, and other regional stores are not in this build.
How are cumulative savings calculated?
Against the prices you actually saw on each product page visit — the cumulative negative-delta sum across the last 90 days for that ASIN. Savings are not measured against list price or a third-party tracker; the running total reflects only the visits the extension observed on your device.
Does it share my browsing data?
No. The extension makes zero remote calls — no fetch, no XMLHttpRequest, no WebSocket, no analytics endpoint, and no third-party price APIs (Keepa, CamelCamelCamel, etc.). The two runtime permissions are storage (to persist your local price history) and activeTab. Every price sample lives in chrome.storage.local on your device.
Is there an affiliate relationship?
Yes — Extensify participates in the Amazon Services LLC Associates Program, an affiliate advertising program. Links on Amazon product pages route through the standard Amazon Associates tag; commissions do not change the price you pay. The full disclosure is included on the extension panel and in the disclosure section above.
Which Amazon stores are supported?
amazon.com only in this build. Adding amazon.co.uk, amazon.de, and other regional stores is on the v0.2 follow-up — once the price-parse path is generalized beyond USD, the matching host_permissions entries are added to the manifest.
More from the blog.
Launch announcements, release notes, and roadmap signals from the Extensify team. New posts go up when something ships — not on a content calendar.
Walkthrough
See every feature in action.
The dedicated walkthrough page goes step-by-step through install, the sparkline panel, the delta badge, and the savings tracker — same content as this post, with anchored install steps and screenshots to make each step obvious.