Viewed Cards Marker

About

Viewed Cards Marker helps users remember what they have already opened, read, or watched on websites they choose.

The extension is designed for content-heavy sites that display items as cards, tiles, or lists. After the user configures a site, the extension can automatically mark an item as viewed when the user opens its detail page, and later highlight the corresponding card or link when that item appears again in listings. This makes it easier to avoid reopening the same content and to visually track progress across large catalogs.

Core features:

Mark cards or links as viewed on supported websites
Work only on sites the user explicitly configures and allows
Support custom CSS selectors and matching rules per site
Automatically mark an item when its detail page is opened
Re-apply viewed markers on list pages
Allow manual mark/unmark controls on cards
Store data locally in the browser
Import and export history/settings as JSON
Optionally sync user data with the user’s own Supabase database

How it works:

The user adds a site configuration in the extension settings.
The user provides the relevant selectors and matching rules for that site.
The user grants access for that specific website.
When the user visits an item page, the extension can save that item as viewed.
When the user later browses list pages, matching cards or links are highlighted as already viewed.

The extension is intentionally user-configured and site-specific. It does not come with a universal scraper or hidden background indexing. The user controls:

which sites are enabled,
which URL patterns are used,
which elements count as cards or links,
how titles/keys are normalized,
whether highlighting is applied to the card or link,
whether viewed state is marked automatically.

Privacy and data handling:

By default, viewed history and site settings are stored locally in extension storage.
Exported backups are created only when the user explicitly requests export.
Optional Supabase sync is user-configured and disabled by default.
The extension is not intended to collect unrelated browsing data.
The extension only operates on websites for which the user has both configured rules and granted permission.

Typical use cases:

Manga or comic websites: highlight titles or chapters already opened
Catalog or gallery websites: mark entries previously visited
Large content libraries: reduce repeat clicks on items the user already checked
Personal workflow sites with repetitive card layouts: track reviewed items visually

Why this extension is useful:
Many websites do not provide a reliable built-in “read” or “viewed” indicator, especially across custom lists, search pages, or community-driven catalogs. Viewed Cards Marker fills that gap by letting the user define exactly how a site should identify an item and how viewed entries should be displayed.

This extension is best suited for advanced users who want control over selectors and matching logic for specific websites. It is flexible enough to support different site layouts while staying focused on one task: showing the user which items they have already viewed.

If you want, I can next turn this into a polished Chrome Web Store submission pack with:

shorter, safer wording optimized for reviewer approval,
store listing title/subtitle variants,
privacy practices text,
and a one-paragraph “How data is used” disclosure.