workshop

keepa-lookup

A tiny Chrome extension: click the toolbar icon on an Amazon product page and it opens that same listing on keepa.com, in a new tab.

How it works

• Reads the ASIN from the current tab’s URL (/dp/ASIN or /gp/product/ASIN), falling back to the data-asin attribute (or canonical link) on the page if the URL doesn’t carry it.
• Maps the Amazon store (amazon.de, amazon.co.uk, etc.) to Keepa’s numeric domainId — Keepa tracks price history per marketplace, and its product URL is https://keepa.com/#!product/<domainId>-<ASIN>.
• Opens that URL in a new tab.

Supported stores: .com, .co.uk, .de, .fr, .co.jp, .ca, .it, .es, .in, .com.mx, .com.br — every store Keepa’s own client maps to a domainId. On any other Amazon marketplace the toolbar badge flashes ?. If the ASIN can’t be found (badge flashes !), the page likely isn’t a standard product listing (search results, cart, etc).

The toolbar icon is greyed out (disabled) except on those stores, via declarativeContent — Chrome has no way for a pinned icon to fully disappear off-page, but a disabled one won’t trigger anything if clicked, so it’s a reliable “is this relevant here” signal. It lights up automatically once you’re on a supported Amazon page; no need to click first to find out.

No build step — it’s plain JS (Manifest V3), loaded directly.

Install (unpacked)

setup.sh checks whether this extension’s path is already in Chrome’s profile — if not, it opens chrome://extensions and copies this directory’s path to your clipboard. From there:

1. Enable “Developer mode” (top right)
2. “Load unpacked” → paste the path (or select this directory, chrome/keepa-lookup/, manually)

Chrome doesn’t offer a way to install an unpacked extension non-interactively (unlike VS Code’s --install-extension), so this one click is unavoidable — setup.sh just gets you to it.

Bump version on changes

setup.sh also flags when the extension’s source has changed since it was last loaded, by comparing manifest.json’s version against the version Chrome has cached for the currently-loaded service worker. When it finds a mismatch it opens chrome://extensions for you, same as the not-loaded-yet case, and tells you to click the reload icon. That comparison is only meaningful if version gets bumped alongside real changes to manifest.json or background.js — do that as part of any change here.