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CompCheck, our first product, is live.Open compcheck.protocat.net

ProtoCat
First product

CompCheck

Reseller research and pricing comps. Enter an item description or marketplace URL, review comparable current asking prices, and get a transparent listing-price range.

Open the CompCheck homepageCompCheck support

Early commercial rollout. The application is not hosted on this parent site. Its address is compcheck.protocat.net.

How it works

  1. 01
    Describe the item
    Type keywords or paste a supported marketplace listing URL.
  2. 02
    Find current comps
    CompCheck queries supported marketplaces for active listings.
  3. 03
    Filter and score
    Weak matches are down-ranked or removed before analysis.
  4. 04
    See the range
    Review asking-price stats and a transparent suggested listing band.

Current capabilities

Taken from the CompCheck application as it is implemented today.

Comparable listing research
Search and normalize current listings from supported marketplaces using official APIs, including the eBay Browse API and Etsy’s Open API where those credentials are configured.
Asking-price analysis
Median, quartiles, and a cautious suggested listing range with written rationale. Asking prices are never labeled as completed sales.
Accounts and usage limits
A free monthly lookup allowance, with optional paid upgrade plumbing when the operator has configured billing credentials.
Demo-safe fallback
When live marketplace credentials are absent, clearly labeled demo fixtures can power local inspection. They are not mixed in as live sold data.

Not in the current version: sold-price comps, scraping of Poshmark, Mercari, Depop, or Vinted, inventory ERP features, or guaranteed sale prices.

Who it is for

Independent resellers and small resale businesses who list on major marketplaces and currently check comps across multiple tabs. That includes thrift, vintage, estate, and closet-clearout sellers who want a faster asking-price band and math they can explain.

Marketplace and trademark notice

CompCheck is an independent product. It is not endorsed, sponsored, certified, partnered with, or affiliated with Etsy, Inc., eBay Inc., or any other marketplace.

Etsy and the Etsy logo are trademarks of Etsy, Inc. CompCheck uses the Etsy API but is not endorsed or certified by Etsy, Inc.

eBay and the eBay logo are trademarks of eBay Inc. CompCheck uses official eBay APIs where configured and is not endorsed by eBay.

CompCheck publishes its own privacy policy and terms. Those documents govern the product. The policies on this site govern protocat.net only.