# GrailHound

> GrailHound is a marketplace alert service for collectors and resellers. You set up a tracker for an item and pick the marketplaces to watch. GrailHound watches them around the clock and alerts you when a new listing matches. It covers 50+ marketplaces, including eBay, Vinted, Facebook Marketplace, Mercari, Depop, Poshmark, Grailed and Craigslist. It runs on the web, iOS and Android, and has a free plan.

- A tracker is one search: a keyword, the marketplaces to watch, optional filters and how to be alerted. Filters cover a price range, words a listing must or must not contain, marketplace categories and AI checks. An AI check reads each matching listing against a plain-language description of what you want. Sellers can be muted or blocked.
- Alerts arrive in the app's feed, by email, as phone push notifications, as browser notifications or as webhooks.
- Free costs $0: 1 tracker, 3 marketplaces per tracker, scans every 30 minutes, 25 AI checks a month. Starter costs $5.99 a month: 3 trackers, 5 marketplaces per tracker, scans every 5 minutes, 500 AI checks a month. Pro costs $14.99 a month: 5 trackers, 10 marketplaces per tracker, scans every 2 minutes, 2,000 AI checks a month. A pay-as-you-go plan, set up on request, can scan every 15 seconds and charges per scan. Every plan can use every marketplace.
- AI assistants connect through GrailHound's MCP server at https://grailhound.app/mcp (Streamable HTTP, sign-in with a GrailHound account over OAuth). Claude, ChatGPT, Gemini and other MCP clients can report what a user's trackers found, run a live test search before a tracker is saved, create and edit trackers, and fine-tune their filters. The server is in the official MCP Registry as app.grailhound/marketplace-alerts.
- GrailHound does not buy, bid or contact sellers. Every match links to the listing on its marketplace.
- The web app is at https://web.grailhound.app. The mobile apps are on the App Store and Google Play.

## Start here

- [GrailHound](https://grailhound.app/): What GrailHound does, how a tracker works, plans and prices, and the main FAQ.
- [AI assistants](https://grailhound.app/ai): Connecting GrailHound to Claude, ChatGPT, Gemini or any MCP-enabled assistant. Example prompts, how an assistant fine-tunes a tracker with a live test search, setup steps for each app, and FAQs.
- [All marketplaces](https://grailhound.app/marketplaces): Every marketplace GrailHound watches, by region. Worldwide: eBay, Vinted, Depop, Facebook Marketplace, Karrot, MercadoLibre, Whatnot. United States and Canada: Craigslist, Mercari, Poshmark, Grailed, OfferUp, Bonanza, Goodwill, Kijiji. Europe: Allegro Lokalnie, Gumtree, Kleinanzeigen, Leboncoin, Marktplaats, OLX, Subito, Tradera, Wallapop, Willhaben. Asia-Pacific: Bunjang, Carousell, Jmty, Joongna, Magi, PayPay Flea Market, Rakuma, Rakuten, Tokopedia, Yahoo Auctions (Japan), Yahoo Auctions (Taiwan), Ruten (Taiwan).

## Marketplace alerts

- [eBay alerts](https://grailhound.app/ebay-alerts): eBay's saved searches notify you once a day. GrailHound watches eBay US, UK, Germany and more, and alerts you within minutes of a new listing going live.
- [Vinted alerts](https://grailhound.app/vinted-alerts): Vinted doesn't send alerts for saved searches. GrailHound watches the Vinted country sites you pick and alerts you when a new listing matches your keywords.
- [Facebook Marketplace alerts](https://grailhound.app/facebook-alerts): Facebook Marketplace's own alerts are hit and miss. GrailHound watches new listings and alerts you when one matches your filters.
- [Mercari alerts](https://grailhound.app/mercari-alerts): Mercari's saved searches have no stated alert schedule. GrailHound watches Mercari and alerts you within minutes of a new listing going live.
- [Depop alerts](https://grailhound.app/depop-alerts): Depop only alerts you inside its app, on its own schedule. GrailHound watches Depop and alerts you when a new listing matches your keywords.
- [Poshmark alerts](https://grailhound.app/poshmark-alerts): Poshmark's saved searches live in its app and stop at thirty. GrailHound watches Poshmark and alerts you when a new listing matches your keywords.
- [Craigslist alerts](https://grailhound.app/craigslist-alerts): Craigslist's saved searches email you on its own schedule, one metro at a time. GrailHound watches Craigslist and alerts you when a new post matches.
- [Allegro Lokalnie alerts](https://grailhound.app/allegro-lokalnie-alerts): Allegro Lokalnie is Allegro's classifieds site for people in Poland selling to each other. GrailHound alerts you when a new listing matches your keywords.
- [Bonanza alerts](https://grailhound.app/bonanza-alerts): Bonanza is a US marketplace of independent sellers, big on fashion and collectibles. GrailHound alerts you when a new listing matches your keywords.
- [Bunjang alerts](https://grailhound.app/bunjang-alerts): Bunjang is a Korean resale app known for K-pop merchandise and brand-name goods. GrailHound alerts you when a new listing matches your keywords.
- [Carousell alerts](https://grailhound.app/carousell-alerts): Carousell is a secondhand marketplace in Southeast Asia, Hong Kong and Taiwan. GrailHound alerts you when a new listing matches your keywords.
- [Grailed alerts](https://grailhound.app/grailed-alerts): Grailed is a resale marketplace for designer, vintage and streetwear fashion. GrailHound alerts you when a new listing matches your keywords.
- [Gumtree alerts](https://grailhound.app/gumtree-alerts): Gumtree is one of the UK's biggest classifieds sites, mostly for local deals. GrailHound alerts you when a new listing matches your keywords.
- [Jmty alerts](https://grailhound.app/jmty-alerts): Jmty is a Japanese local classifieds site for selling and giving away things nearby. GrailHound alerts you when a new listing matches your keywords.
- [Joongna alerts](https://grailhound.app/joongna-alerts): Joongna is a Korean secondhand marketplace where Lego is the top search. GrailHound alerts you when a new listing matches your keywords.
- [Karrot alerts](https://grailhound.app/karrot-alerts): Karrot is a neighborhood buy-and-sell app in Korea, the US and Canada. GrailHound alerts you when a new post in your areas matches your keywords.
- [Kijiji alerts](https://grailhound.app/kijiji-alerts): Kijiji is Canada's local classifieds site. GrailHound keeps a constant watch on it and alerts you when a new ad matches your keywords.
- [Kleinanzeigen alerts](https://grailhound.app/kleinanzeigen-alerts): Kleinanzeigen is Germany's biggest classifieds site. GrailHound keeps a constant watch on it and alerts you when a new listing matches your keywords.
- [Leboncoin alerts](https://grailhound.app/leboncoin-alerts): Leboncoin is France's biggest classifieds site. GrailHound keeps a constant watch on it and alerts you when a new listing matches your keywords.
- [Magi alerts](https://grailhound.app/magi-alerts): Magi is a Japanese trading card marketplace for Pokémon, One Piece and Yu-Gi-Oh! cards. GrailHound alerts you when a new listing matches your keywords.
- [Marktplaats alerts](https://grailhound.app/marktplaats-alerts): Marktplaats is the biggest marketplace in the Netherlands, for new and secondhand goods. GrailHound alerts you when a new listing matches your keywords.
- [MercadoLibre alerts](https://grailhound.app/mercadolibre-alerts): MercadoLibre is Latin America's biggest online marketplace. GrailHound keeps a constant watch on it and alerts you when a new listing matches your keywords.
- [OfferUp alerts](https://grailhound.app/offerup-alerts): OfferUp is a US app for buying and selling locally. GrailHound keeps a constant watch on it and alerts you when a new listing matches your keywords.
- [OLX alerts](https://grailhound.app/olx-alerts): OLX runs classifieds sites in Poland, Romania, Ukraine, Bulgaria and Portugal. GrailHound alerts you when a new ad on any of them matches your keywords.
- [PayPay Flea Market alerts](https://grailhound.app/paypay-flea-alerts): Yahoo!フリマ, formerly PayPay Flea Market, is a Japanese flea market app. GrailHound alerts you when a new listing matches your keywords.
- [Rakuma alerts](https://grailhound.app/rakuma-alerts): Rakuma is Rakuten's flea market app in Japan. GrailHound keeps a constant watch on it and alerts you when a new listing matches your keywords.
- [Rakuten alerts](https://grailhound.app/rakuten-alerts): Rakuten Ichiba is Japan's biggest online shopping mall. GrailHound keeps a constant watch on it and alerts you when a new listing matches your keywords.
- [Ruten alerts](https://grailhound.app/ruten-alerts): Ruten is a Taiwanese marketplace with peer to peer sales and auctions. GrailHound alerts you when a new listing matches your keywords.
- [ShopGoodwill alerts](https://grailhound.app/goodwill-alerts): ShopGoodwill is Goodwill's online auction site for donated goods. GrailHound alerts you when a new listing matches your keywords.
- [Subito alerts](https://grailhound.app/subito-alerts): Subito is Italy's top secondhand marketplace, and collectibles are its biggest category online. GrailHound alerts you when a new listing matches your keywords.
- [Tokopedia alerts](https://grailhound.app/tokopedia-alerts): Tokopedia is an Indonesian online marketplace. GrailHound keeps a constant watch on it and alerts you when a new listing matches your keywords.
- [Tradera alerts](https://grailhound.app/tradera-alerts): Tradera is Sweden's biggest secondhand marketplace, and collectibles are its biggest category. GrailHound alerts you when a new listing matches your keywords.
- [Wallapop alerts](https://grailhound.app/wallapop-alerts): Wallapop is a secondhand app in Spain, Italy and Portugal. GrailHound keeps a constant watch on it and alerts you when a new listing matches your keywords.
- [Whatnot alerts](https://grailhound.app/whatnot-alerts): Whatnot is a live shopping app best known for sports cards and trading card games. GrailHound alerts you when a new listing matches your keywords.
- [Willhaben alerts](https://grailhound.app/willhaben-alerts): Willhaben is Austria's biggest online marketplace, with over 4 million users. GrailHound alerts you when a new listing matches your keywords.
- [Yahoo Auctions Japan alerts](https://grailhound.app/yahoo-auctions-jp-alerts): Yahoo Auctions is one of Japan's biggest auction sites, known for rare items and trading cards. GrailHound alerts you when a new listing matches your keywords.
- [Yahoo Auctions Taiwan alerts](https://grailhound.app/yahoo-auctions-tw-alerts): Yahoo Auctions Taiwan has millions of listings, with peer to peer sales and auctions. GrailHound alerts you when a new listing matches your keywords.

## Guides

- [AI checks](https://grailhound.app/ai-checks): How an AI check reads each matching listing against your own description, used as a filter on a tracker or on your alerts.
- [High Importance notifications](https://grailhound.app/high-importance-alerts): Phone notifications that can break through Do Not Disturb, and how to turn them on.
- [Webhooks](https://grailhound.app/webhooks): Developer reference for receiving each new match as a signed JSON POST on your own HTTPS endpoint: setup, every payload field, HMAC-SHA256 signature checks with Node.js, PHP and Python samples, and the retry and auto-disable rules.

## Data

- [How fast do collectibles sell?](https://grailhound.app/how-fast-do-collectibles-sell): A benchmark of over 100,000 fixed-price eBay sales across more than 50 collectible categories, measuring the time from listing to sale.
- [Sell-speed data, every sale (CSV)](https://grailhound.app/data/how-fast-do-collectibles-sell-all-sales.csv): One row per confirmed sale behind that benchmark. Columns: item name, eBay URL, date listed, date sold (UTC). The page asks for credit with a link.
- [Sell-speed data, sales within 30 minutes (CSV)](https://grailhound.app/data/how-fast-do-collectibles-sell-fast-sales.csv): The same columns, for the sales that happened within 30 minutes of listing.
- [Which Vinted countries can you buy from?](https://grailhound.app/vinted-alerts#map): A measured map of which countries' sellers each Vinted country site (vinted.fr, vinted.pl, vinted.co.uk and the rest) shows its buyers, with every country's connections written out in the page. Re-measured from the live catalogs. The page states the measurement date.
- [Vinted reach matrix, raw data (JSON)](https://grailhound.app/data/vinted-shipping-matrix.json): The dataset behind that map, CC BY 4.0. Keys: `portals` (per buyer site: `seller_countries` as distinct sellers per ISO country code), `matrix` (buyer → seller country → sellers), `reaches` (confirmed foreign seller countries per buyer site), `reachable_from` (the inverse), `asymmetries` (one-way pairs), `measured_at`, `method`. Country codes are ISO 3166-1 alpha-2. `GB` is the United Kingdom.

## Notable finds

- [Hall of Fame](https://grailhound.app/hall-of-fame): Documented marketplace sales of rare items. Each find has its own page with the verified sale price and the original listing photos.
- [1966 Donruss Marvel Spider-Man #34, PSA 9](https://grailhound.app/1966-marvel-spider-man-34-psa-9): Sold on eBay for $175,100 in August 2026 after 218 bids.
- [LeBron James' 2022 NBA All-Star Game jersey](https://grailhound.app/lebron-james-2022-all-star-jersey): Sold on eBay for $800 in June 2026, titled like a replica. Appraisers told The Athletic it is worth $140,000 to $250,000.
- [2015 Pokémon World Championships No. 1 Trainer](https://grailhound.app/pokemon-2015-worlds-no-1-trainer): A trophy card graded CGC 8, sold on eBay for $68,000 after nearly nine months listed.
- [Frits Henningsen high-back wing chair, c. 1935](https://grailhound.app/frits-henningsen-wing-chair): Bought for $50 on Facebook Marketplace and sold at Sotheby's four months later.
- [John Lennon's Fender Deluxe amp](https://grailhound.app/john-lennon-fender-deluxe-amp): A mid-1960s Fender Deluxe with a handwritten note from Rod Lynton saying John Lennon told him to keep it, bought on Facebook Marketplace for under £3,000.
- [Clear Nintendo 64DD prototype](https://grailhound.app/clear-64dd-prototype): Listed on Mercari Japan as-is and sold for ¥1,100,000 about two hours after going up.
- [Pre-Tyson Punch-Out!! NES prototype](https://grailhound.app/punch-out-nes-prototype): Sold at Heritage Auctions for $45,000 with the buyer's premium. Two weeks later the ROM went public.
- [Yu-Gi-Oh Cyber-Stein SJC-EN001, PSA 10](https://grailhound.app/yugioh-cyber-stein-prize-card): A 2004 Shonen Jump Championship prize card, sold on eBay for $29,999.99.
- [Hudson Computer Designers School album, 1993](https://grailhound.app/hudson-school-graduation-album): The graduation album of Hudson Soft's game design school, with its students' games.
- [Bad to Worse publishing demo](https://grailhound.app/bad-to-worse-acetate-publishing-demo-from-unidentified-artist): A single-sided demo acetate of the soul song, cut for Metric Music in London and not credited to an artist.

## Optional

- [Privacy policy](https://grailhound.app/privacy): What GrailHound stores, why, and the controls users keep. Section 2.4 covers AI assistant connections.
- [Terms](https://grailhound.app/terms): The terms for using GrailHound.