COMC Purchase History Helper

See “Purchased” badges on COMC product pages and make card collecting easier.

Ever wonder, "Have I bought this card before?" while browsing COMC? COMC Purchase History Helper is a Chrome extension that uses the purchase-history CSV available from COMC's Purchases History page to display "Purchased" badges on COMC listings and product pages. It helps you check past purchases even after cards have been shipped and are no longer in your Inventory. Features • Import purchase-history CSV files by selecting a file or dragging and dropping it. • Follow on-screen instructions to download and import your first CSV. • See purchase-history badges on COMC listings and product pages. • Click a badge to view the selected card's purchase dates, USD prices and other details in the side panel. • Search history by card type and view purchase dates, USD prices and other details. • Back up and restore history using JSON files. • Choose Automatic, Japanese or English for the interface. • Use a wider popup or click "Open full view" to work in a regular tab. Supported views COMC's Details, List and Text views are supported. Thumbs is not supported. There are no fixed restrictions based on listing count, sorting, pagination, filters or sport. Graded cards are also matched by card type. Products with insufficient information or unsupported page structures are not marked as confirmed purchases. How to use 1. Download your CSV using "Download Purchase History" on COMC's Purchases History page. 2. Open the extension from Chrome's toolbar and click "Open full view". 3. Under "Import purchase history CSV", select your CSV or drag it into the import area. Review the preview and click "Confirm import". 4. Purchase-history badges appear on supported COMC pages. Click a badge to view that card's history in the side panel. Import the latest CSV again to update your history after new purchases. There is no automatic synchronization. Reimporting the same purchase records does not add duplicates. How your data is handled The selected CSV is read within Chrome. After confirmation, purchase records and settings are saved in this Chrome profile. Public product information and URLs on the page you are viewing are processed locally to match your imported history. To maintain the side panel selection, only the last clicked public product is temporarily kept per window. This temporary storage contains no URLs or purchase records; the selection is cleared when its window closes, Chrome restarts or the extension updates. The extension does not send history to external servers, use analytics or sync data to the cloud. Stored data and JSON backups are not encrypted. Page scripts may be able to see the badges. You can turn badges off in Settings. Purchase dates, prices, record counts and purchased ItemIDs are shown only inside the extension, not in page badges. Before you use it • Badges indicate purchase history for the same card type. They do not guarantee current ownership, the same physical item, or the same grading company, grade or condition. • Return flags, conflicts and uncertain matches are marked for review. No badge is not proof that a card has never been purchased. • Results cover only your imported CSV records. Dates retain the CSV's recorded values without timezone conversion. • CSV files must be UTF-8, with a maximum of 10 MiB and 5,000 rows per file. Up to 5,000 purchase records can be stored, subject to storage capacity limits. • History stays in this Chrome profile after you log out of COMC. Uninstalling the extension deletes it, so export a backup when needed. • The extension does not log in to COMC, crawl pages, make purchases, modify carts or make offers. Developer: Takumetal Contact: X @takumetal55 (DM, reply or mention) https://x.com/takumetal55