Facebook Marketplace Saved Search Alert

WHAT IT DOES

This userscript adds saved search alert functionality to your Facebook Marketplace browsing experience. It reads listing data from the page—extracting titles, prices, locations, and listing dates—and compares them against your stored saved searches (keywords, price ranges, locations). When a listing matches one of your saved searches, a color-coded alert badge appears: blue for new matches, green for price drops, and yellow for recently listed items. A summary panel shows the total number of new matches and price drops. The script tracks which listings you've seen and remembers previous prices, so it can detect when a listing's price has dropped. A desktop notification is sent when new matches are found. This is invaluable for deal hunters, resellers, and bargain shoppers who need to monitor specific items, get alerted to price drops, and never miss a new listing that matches their criteria.

WHERE IT RUNS

The script runs on all Facebook web application pages at *.facebook.com/*, with automatic detection of Marketplace search results, category pages, and any page displaying listing items. It works across all Facebook interfaces by using multiple selector strategies to find listing items, titles, prices, locations, and listing dates. The script detects dynamic content loading and re-runs the search when new listings are loaded. It runs across the entire Facebook domain, ensuring coverage whether you're browsing the main Marketplace feed, a specific category, or search results.

HOW TO USE

Install the script via the BotGentz extension and navigate to any Facebook Marketplace search results page. The script will automatically scan listings and display alert badges on matching items. Use the panel controls to manage your saved searches: add a new search with a name, keywords (comma-separated), and an optional price range (Min-Max). Toggle alert badges on or off, enable or disable notifications for new matches, show or hide price drop alerts, or set auto-refresh on page load. The summary panel shows the number of new matches and price drops. Click the ↗ button next to any matched listing to open it in a new tab. The "Clear seen listings history" button resets the tracking of which listings you've seen.

THE MECHANISM - LISTING EXTRACTION, SEARCH MATCHING, AND PRICE DROP DETECTION

This script identifies listing data by scanning the DOM for known Facebook Marketplace elements using a cascading selector strategy. It extracts titles from title elements, prices from price elements, locations from location elements, and dates from date elements or relative time strings. Each listing is assigned a unique key based on its title, price, and location. Saved searches are stored in GM_setValue and include name, keywords array, minPrice, maxPrice, and location. The matching algorithm checks each listing against all saved searches: keywords are matched by checking if any keyword appears in the title, price must fall within the min/max range, and location must contain the saved location string. The script tracks seen listings and their last known prices in a separate GM_setValue object. A listing is marked as "new" if it hasn't been seen before, and "price drop" if the previous price was higher. The badge is created as a DOM element with inline styles and inserted into the listing title cell.

THE PANEL

The control panel appears as a floating, draggable element that you can position anywhere on the Facebook page. Drag by the header to reposition it, and the position is saved per site using GM_setValue so it stays where you left it across sessions. Release the panel near any edge and it snaps into place, keeping your workspace organized. Click the panel header to collapse it into a small bubble showing only the bell emoji (🔔), minimizing distraction while keeping controls accessible. Drag from the bubble to restore the full panel. The panel automatically resizes to fit its content and includes all setting toggles, saved search management, and action buttons. Press the Escape key to quickly collapse the panel to its minimized state. The panel remains visible across page navigation within Facebook, with the search running automatically as you browse different Marketplace views.

PLEASE NOTE

This script requires the free BotGentz extension to function. It is designed for Facebook Marketplace users who want to monitor listings matching specific criteria. The script reads only visible listing data from the DOM—it does not access Facebook's API, your account credentials, or any sensitive information. All settings (badge visibility, notification toggle, price drop toggle, auto-refresh, saved searches, and seen listings) are stored locally using GM_setValue and never leave your browser. The script does not modify your Facebook data—it only reads and visualizes visible listing information. The script relies on the structure of Facebook Marketplace pages; if Facebook updates its website structure, the script may need to be updated to match new selectors. Price drop detection requires the listing to have been seen previously with a higher price; the first time a listing is seen, it will not trigger a price drop alert.