Browser extension

Check a cart on someone else’s shop

The web app answers “is this cart right for me” inside PatchTest. The extension answers it where people actually shop. It reads the cart on a shop’s own page, matches each product title to its active ingredients and strengths, and applies the same cited rules there.

Download the extensionv1.0.0 · zip · Chrome, Edge, Brave, Arc

It is not on the Chrome Web Store, so it loads unpacked. That is the normal way to run an unlisted extension and takes about thirty seconds. Nothing to configure, and no account.

Install it

  1. 1

    Download the zip and unzip it

    patchtest-extension-v1.0.0.zip. Unzip it somewhere you will not delete by accident. The browser loads the extension from this folder every time it starts, so moving or binning it later uninstalls it.

  2. 2

    Open your browser’s extensions page

    Paste chrome://extensions into the address bar and press Enter. On Edge it is edge://extensions, on Brave brave://extensions. A link will not work here; it has to be typed or pasted.

  3. 3

    Turn on Developer mode

    The toggle sits in the top-right corner of that page. Without it, the Load unpacked button in the next step does not appear.

  4. 4

    Press Load unpacked, and pick the unzipped folder

    Choose the folder itself, not a file inside it. It is the one containing manifest.json. PatchTest now appears in your extensions list.

  5. 5

    Pin it to the toolbar (optional)

    Press the puzzle-piece icon beside the address bar and pin PatchTest, so the check button is one click away on any shop.

Use it

  1. 1

    Give it a profile to work from

    Run any preset or a scan of your own on the check page. The results page leaves your profile in this browser for the extension to pick up. Until you do this, the extension has nothing to judge a cart against and will say so.

  2. 2

    Open a cart

    Verdant Row is a second fictional shop built for exactly this, with a deliberately awkward cart in it. The extension annotates the cart in place.

  3. 3

    Run it anywhere else

    On any other shop, press the toolbar icon and then Check this page. It reads product titles out of the page and returns a verdict for each one it can parse.

What it sends, and what it does not

  • No photo ever leaves your machine. The extension never touches your scan image. Your profile is your declared intake plus the label of your recorded scan, and it stays in the browser’s own storage until you press check.
  • It only reads a page when you ask. There is no background scraping and no tracking. On the demo shop it annotates the cart on load; everywhere else it waits for the button.
  • A title it cannot read never comes back “OK”. It says it could not read the product, and says plainly that this is not a safety clearance. The parser does not guess.

If something goes wrong

The Load unpacked button is missing
Developer mode is still off, or you are on a browser that is not Chromium-based. Safari and Firefox use different extension formats and this build will not load in them.
It says it has no profile
Run a preset on the check page first, in the same browser profile. A different browser profile, or a private window, has its own storage and will not see it.
Nothing appears on a shop’s cart
Press the toolbar icon and Check this page. If the products still get no verdict, the shop’s titles do not name an active ingredient or a strength, which is the one thing the rules key on.
The extension disappeared after a restart
The unzipped folder was moved or deleted. Put it back, or load it unpacked again.

The source is in the repository if you would rather read it before running it, or load that folder directly instead of the zip.