Underpriced AIEvery marketplace and app, and how it connects
Some marketplaces we publish to. Some we fill in for you to post. Some get a copy kit. Here is which is which.
Then $0.25 a scan, or plans from $5 a month. 4,600+ resellers have priced $2.4M+ of items.
Updated
Publishes from the app
eBay in 10 countries, Bonanza, and Discogs for records. Any device.
Extension fills it, you post
Facebook Marketplace, Poshmark, Mercari, Depop, Vinted, Whatnot, OfferUp and Etsy, plus District, Craigslist, 1stDibs and Ruby Lane. On a computer.
Copy kit, you paste
Poshmark, Mercari, Facebook, Depop, Vinted and OfferUp. On a phone.
One real scan and the sales behind it
The sales behind a price like this
In the 90 days to September 28, our archive captured 332 eBay sales matching “lady head vase”. The middle half went for $29.99 to $74.99.
The scan priced ours at $34.30, low in that spread; it sold for $45. Every scan lists the sold listings behind its price, each one a link to eBay, like these three from the archive:
- Low quarterVintage Lady Head Vase Planter Brown Hair Gold Bow Collar Ceramic Figurine$29.99
- Middle saleVintage Lady Head Vase Napco Brunette with Hand, Miniature 4.5 in, circa 1958$45
- High quarterVintage Inarco E-3524 Lady Head Vase Glamour Girl 7 in Blonde Pearl Necklace$74.99
The vase is a real find by a reseller in our family. Sales from our archive of eBay sold listings, read September 28, 2026.
Graded every week against 379 real sales, published win or lose. See the grade
The figures
On the 195 sales in the last 90 days where the seller set their own price, the typical gap between our estimate and the sale was 38%, and 41.5% sold inside our range. That is why every result shows a range and the sales, not one confident number.
Publishes from the app
Connect your own account once and the listing goes live from the app. One tap, on any device.
The eBay listing tooleBay
Publishes from the app
US, UK, Canada, Australia, Germany, France, Italy, Spain, Netherlands and Belgium. Item specifics, auctions, scheduling, Best Offer rules, Promoted Listings, price changes, end and relist, sale sync, and importing your active listings.
Bonanza
Publishes from the app
Publish the same listing to Bonanza from the item page.
Discogs
Publishes from the app
Records publish to Discogs, matched to the right release.
On a computer: the extension fills it, you post
A free extension for desktop Chrome, Edge and Firefox. It fills the marketplace's own form with your title, price, description and photos; you pick the category and click Post.
How the extension worksFacebook Marketplace, Poshmark, Mercari, Depop, Vinted, Whatnot, OfferUp and Etsy
Extension fills the form
Title, price, description and photos filled in on each marketplace's own create listing page. You pick the category and click Post.
District, Craigslist, 1stDibs and Ruby Lane
Extension fills the form
The same form fill. District also takes a bulk import CSV from the item page.
On a phone: a copy kit
Extensions do not run on phones, so the item page shares your photos and copies each field in the order the form asks. The same marketplaces as above, done by hand in a few taps. StockX gets a copy and open on any device.
Poshmark, Mercari, Facebook, Depop, Vinted and OfferUp
Copy kit
Photos first, then one Copy button per field, then open the marketplace app and post.
StockX
Copy kit
Copies your ask and the title and opens the StockX search; you pick the catalog product.
Where prices and details come from
Sold prices, not asking prices, from five sources tried in order.
How a price is madeeBay sold listings
Reads from
Two sold-price services, a broader search when an item is described too narrowly, our own read of eBay sold results, then our archive of over a million recorded sales.
Google Books
Reads from
An ISBN in the photo pins the exact edition.
Discogs
Reads from
A CD or record barcode pins the exact release.
Finding the next haul
Sale Finder on Pro Plus and up: type your ZIP once and each site opens filtered to your area.
Sale FinderEstateSales.NET, GSALR, YardSaleSearch and AuctionZip
Opens with your search
Ready made searches for estate sales, garage sales, yard sales and auctions near you.
Inside your AI assistant
Add Underpriced AI to the AI chat you already use and ask it about an item. It never publishes on its own.
Set it upChatGPT and Claude
Connector
Price an item, pull the sold listings, check if a buy is worth it, draft an eBay listing.
Coding tools (Cursor, VS Code)
Connector
The same tools, for developers building on them.
Where it runs
One account everywhere.
iPhone
Runs on
The App Store app, with the native camera.
Android
Runs on
The Google Play app, with the native camera.
Web
Runs on
Any browser, phone or computer. Nothing to install.
Chrome, Edge and Firefox
Runs on
Right click any product image online and scan it; fill other marketplaces' forms.
Files and printers
For the parts that live outside the app.
Excel and Google Sheets
Exports
Export your items or your scan history as a CSV on every plan.
Your tax preparer
Exports
A Schedule C ready CSV with revenue, cost of goods, fees, shipping and other expenses, on Pro Plus and up.
Avery, Dymo, Rollo and Brother
Exports
Barcode labels on Avery 5160 sheets or 2.25 by 1.25 inch thermal labels. Scan a label to open the item.
What it does not connect to
- Amazon: items get tap to copy fields and a link to Seller Central, not a form fill.
- No marketplace other than eBay can be ended or delisted from the app.
- No automatic crossposting: every listing outside eBay, Bonanza and Discogs is posted by you.
The whole app, feature by feature: the reseller app and the eBay listing tool.
Questions
- Which marketplaces can Underpriced AI post to directly?
- eBay in ten countries and Bonanza, from inside the app on any device, and Discogs for records. Every other marketplace is filled in by the extension or copied field by field for you to post.
- Does the extension post for me?
- No. It opens the marketplace's own create listing page in your logged in browser and fills the title, price, description and photos. You pick the category, check the details and click Post. It runs in your browser, so we never see your marketplace logins.
- Does it work on a phone?
- Scanning, pricing, eBay and Bonanza publishing all work on the iOS and Android apps and the mobile web. The form-filling extension needs a desktop browser. On a phone, the item page shares your photos and copies each field in the order the marketplace asks, and you paste them in its app.
- Will it delist an item when it sells on another marketplace?
- It can end the eBay listing for you when you mark an item sold elsewhere, if you turn that on in Settings, and it emails a reminder for the other marketplaces. It cannot end listings on Poshmark, Mercari or Facebook for you.
- Can I use it inside ChatGPT or Claude?
- Yes. Add Underpriced AI to Claude or ChatGPT and ask it to price an item, pull the sold listings, check whether a buy is worth it, or draft an eBay listing. It never publishes on its own.
Your first scan is free with no card. Then pay as you go at $0.25 a scan, buy a 5 scan pack for $3, or pick a plan from $5 a month for 30 scans. Compare plans.