CompsAPI alternative: price the photo, not the keyword
CompsAPI is an eBay sold listings API: type a keyword, get up to 240 completed sales as JSON with up to three years of history. Underpriced AI starts from a photo, prices it from real eBay sold comps, and takes it through to a listing. Both run inside Claude. First scan free.
Underpriced AI vs CompsAPI
| Feature | Underpriced AI | CompsAPI |
|---|---|---|
| Identify any item from a photo | Keyword search; photo input not stated | |
| Barcode scanning (books, CDs, vinyl) | Not stated | |
| Real sold comps with clickable links to verify | Up to 240 eBay sold listings per request, up to 3 years back, with links and real Best Offer prices | |
| Sold data across eBay, Poshmark, Mercari | eBay only (US plus UK, DE, FR, IT, ES, CA, AU); more marketplaces listed as on the roadmap | |
| Live active listings | Not stated (sold listings only) | |
| Market saturation + category sell-through | Not stated | |
| Platform fee / take-home calculator | Not stated | |
| Weekly portfolio email: value, what sold, what's trending | Not stated | |
| AI-generated listing title + description | Not stated | |
| Direct eBay publishing (10 markets) | Not stated | |
| Bonanza publishing | Not stated | |
| Cross-listing (one-click autofill) | eBay, Facebook, Poshmark, Mercari, Depop, Vinted, Whatnot, OfferUp, Etsy + | Not stated |
| One-tap reprice / refresh value | Not stated | |
| Inventory management (death pile, storage, tags) | Not stated | |
| Purchase price + profit/loss tracking | Not stated | |
| Analytics dashboard (ROI, aging, sourcing) | Median, mean, quartiles, outliers removed; Google Sheets template | |
| Estate & garage sale finder | Not stated | |
| Platforms | iOS, Android, Web, extension | REST API, Google Sheets template; apps not stated |
| AI model | Claude Opus 5.5 | Rules that read listing titles (card grades, junk flags); no vision stated |
| Free first scan, no card | 100 free requests a month, no card | |
| Sold prices from more than one source, with automatic failover | eBay only | |
| Works inside ChatGPT, Claude and coding assistants (MCP) | Hosted MCP server with one keyword tool (Claude, Cursor); API key required | |
| Scan packs, no subscription required | 5 scans for $3 | Monthly plans with $2 per 1,000 overage; packs not stated |
| eBay Promoted Listings at your own ad rate | Not stated | |
| Pricing accuracy measured against real sales and published | Publishes a 49-sale Best Offer price check; estimate accuracy not stated | |
| Starting price | Free scan, then $5/mo or a $3 5-scan pack | Free 100 requests/mo (90 days of history); $9/mo for 5,000; $29/mo for 25,000 with 3 years of history |
CompsAPI facts checked 2026-10-09 against compsapi.com. “Not stated” means their public material does not say; it is not a no. Their features and prices can change.
What CompsAPI does well
Depth. One request returns up to 240 eBay sales, and from the $29 plan the history runs 1,095 days, so a developer can price by trend instead of a 90-day snapshot. It returns the price a Best Offer actually closed at, not the asking price eBay's sold page keeps showing. Eight eBay country sites, a trading-card layer, a Google Sheets template, and a hosted MCP server for Claude and Cursor.
Where Underpriced AI goes further
CompsAPI assumes you already know the keyword. At an estate sale you usually do not. Underpriced AI identifies the item from the photo, pulls the real eBay sold comps, and returns a calibrated estimate with a range, three list prices with a two-week sell chance, and the net after fees. Then it drafts the eBay listing, crosslists through the extension, and tracks the profit.
Choose Underpriced AI if you
- Start from a photo, not a keyword
- Want the listing drafted and the profit tracked
- Crosslist to Poshmark, Mercari, Facebook, Depop or Etsy
- Ask Claude or ChatGPT what a find is worth
CompsAPI may fit if you
- Build pricing software and need sold data as JSON
- Need three years of eBay history for seasonality
- Price watches or cards where accepted Best Offers hide the real price
- Want eBay medians in a Google Sheet
Common questions
How is Underpriced AI different from CompsAPI?
CompsAPI is a data feed: a keyword returns up to 240 eBay sold listings as JSON with a median and the real accepted Best Offer price. Underpriced AI starts from a photo, works out what the item is, prices it from real eBay sold comps, then drafts the eBay listing, crosslists and tracks the profit.
What does CompsAPI cost compared to Underpriced AI?
On compsapi.com on 2026-10-09: Free is 100 requests a month with 90 days of history, no card; Starter $9 a month for 5,000; Growth $29 for 25,000 with three years; Pro $79 and up. Underpriced AI: free first scan, then Starter $5 a month for 15 scans, Pro $15 for 75, Pro Plus $29 for 200, or a $3 pack of 5 scans.
Do both work inside Claude?
Yes. CompsAPI's docs describe a hosted MCP server with one tool, search_sold_listings, that takes your API key. Underpriced AI's connector has five tools; the description price and sold-comps lookups work a few calls a day without an account.
Can CompsAPI price an item from a photo?
Its site and docs describe keyword search and say nothing about photo input, so the table marks it not stated. Underpriced AI reads the brand, marks, size and condition from the photo.
Does either one list the item on eBay?
CompsAPI's material covers sold data, an API and a Google Sheets template, nothing about listing. Underpriced AI drafts the eBay listing from the scan; from Claude the draft waits in the app until you review and publish it.
See what it really sold for
Your first scan is free. No card.
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