Deck Compare — Privacy Policy

Last updated: November 4, 2026

Overview

Deck Compare is a browser extension for Chrome, Edge and Firefox that compares Magic: The Gathering decklists. It runs entirely in your browser: there is no account, and nothing about you or your decks is collected. The only thing sent to the author's server is anonymous usage statistics, which you can switch off (see below).

Data we collect

No personal information and no browsing history. The developer only receives the anonymous usage statistics described under "Analytics and tracking".

What the extension reads

• Decklists (card names, quantities and the deck's name) from the deck pages you open or the deck links you give it, on the supported sites: Moxfield, Archidekt, MTGGoldfish, mtgtop8, Magic-Ville, mtgdecks, Melee, getpaird, ManaBox, Pauper Duel Commander and Endstep; and from decklists you paste yourself. On Endstep, where decks belong to an account, the deck is read from the site's own deck service, in the tab where you are signed in, with that tab's session; the extension never sees your Endstep password.
• The address of the tab you are on, when you click the extension's icon, to recognise a supported deck page.
• Your open tabs on the supported deck sites (their address and title, in every window), when you open the extension's popup, the Compare panel on a deck page or the results page's "Compare another" menu, to offer them as the second deck. The Compare panel shows them inside the page in a closed area that the site's own scripts cannot read. Tabs on other sites are never read.
• Your public decks, if you enter your username for Moxfield, Archidekt or Magic-Ville: the list of that user's public decks on that site.

The extension only reads decks. It never posts, edits or changes anything on these sites.

Network requests

The extension contacts only the following:

• The supported deck sites, to fetch the decks you chose to compare. Requests to MTGGoldfish, mtgdecks and Magic-Ville carry the cookies your browser already holds for those sites, so that their bot protection lets them through; the extension never reads or stores those cookies. When one of these sites blocks a direct request, the extension opens the deck page in a background tab, reads it and closes it. ManaBox decks are always read that way, from the deck page (the tab you already have open, or a background tab opened for it), never through a request of the extension's own.
• stats.tolarianstudio.com, the author's own server, for the anonymous usage statistics described under "Analytics and tracking" (unless you switch them off).
• Tally (tally.so), only if you click "Feedback and ideas": the form opens there, and its address tells it the extension's version, your browser and the page you clicked from. What you type in the form goes to Tally; the email field is optional. See Tally's privacy policy.
• Scryfall (api.scryfall.com, cards.scryfall.io), to get card types and images: the names of the cards on screen are sent to Scryfall for that purpose. See Scryfall's API terms.

The typefaces of the extension's own pages ship inside it: no font is downloaded.

Stored on your device

The extension keeps the following in the browser's extension storage (storage.local), on your device only:

• the two decks of the comparison in progress, so the results page can show them;
• the decks you add to a cross-comparison, the card filters you set on it, and your own list if you compare it to them;
• your settings: whether the Compare button shows on deck sites, the usernames you entered and the public deck lists fetched for them, and the results page's display density;
• a cache of card data from Scryfall (card types and image addresses), kept for 30 days so pages load faster (a card name Scryfall does not know is remembered as such for a day).

Nothing is synced across devices or sent anywhere. Uninstalling the extension deletes all of it.

Sharing a comparison

The results page's Share button copies a link that holds the comparison itself: the two decks' names, sites and addresses, their card lists and the day it was shared, compressed after the # of the address. The extension sends this link nowhere: you choose where to paste it, and anyone you give it to can read the decks it holds.

Whoever opens the link sees the comparison on a page of this project's site, mcouzinet.github.io/deckCompare, hosted by GitHub Pages, with or without the extension. Browsers never send the part of an address after the #, so GitHub only receives the request for the page itself, as for any website (see GitHub's privacy statement). The page reads the decks from the link in the reader's browser, asks Scryfall for the card types and images as the extension does, and stores nothing on the reader's device.

Permissions

• activeTab: read the address and the decklist of the tab you are on, when you click the extension's icon.
• storage: keep the data listed above on your device.
• scripting: show the Compare button on the optional sites you allow, and read the deck there, or on the tab you are on when you click the extension's icon.
• Access to the supported deck sites and Scryfall: read decklists and card data, and show the Compare button on deck pages. On Firefox, you grant this access from the extension's popup the first time.
• Optional access to Moxfield's pages, to ManaBox, Pauper Duel Commander and Endstep, and to the www / non-www variants of the supported sites: requested only from a click: in the extension's popup (the Compare button setting, or "Allow the button" on one of these sites) and, for ManaBox, Pauper Duel Commander and Endstep, when you ask the extension to read one of their deck links. It is removed when you turn the button off. Apart from the ManaBox deck open in the tab where you click the extension's icon, decks from these three sites can only be read with this access.

Analytics and tracking

To know how many people use it, the extension sends a few anonymous signals to stats.tolarianstudio.com, the author's own server:

• when it is installed or updated: the event, the extension's version and the browser's name (Chrome, Edge, Firefox or Safari);
• at most once a day while the browser runs: the same, plus a random identifier drawn when the extension is installed. It identifies nothing but this installation and only serves to count each device once; it is kept 120 days;
• when it is uninstalled, the browser opens a short page on that server, which counts the uninstall (version and browser name).

Nothing else is ever sent: no deck, card, page visited, or anything you type. The server does not record IP addresses. The figures are only used by the author, as totals. You can switch this off at any time in the extension's settings ("Anonymous usage statistics"): from then on nothing is sent and no page opens on uninstall. On Firefox it is only sent if you allowed "technical and interaction data" when installing; on Safari, only once you tick the setting.

No advertising, and the extension sets no cookies of its own.

The presentation page

The extension's presentation page, deckcompare.tolarianstudio.com, counts its visits and the clicks on its store buttons with Umami, hosted on the author's own server: no cookie, no personal data, no IP address kept. The extension itself sends nothing of the kind.

Changes to this policy

Changes are published on this page, with a new date at the top.

Contact

For any question about this policy, open an issue on GitHub.