Buy and sell with Verified confidence
The TAGBASE Browser Extension lets buyers and sellers instantly verify authenticity and proof of ownership on eBay, Vinted, Depop, Mercari, and Willhaben.
Download ExtensionTwo major challenges in secondary marketplaces
Platforms face trust issues that cost buyers and sellers billions every year.
No physical Access
Sellers list items they don't actually possess—dropshipping scams, warehouse fraud, or simply items they never had. Buyers pay for products that may never arrive or don't exist at all.
No proof of ownership
Sellers may have physical access to items, but aren't the rightful owners. Stolen goods, borrowed items, or products from fraudulent sources end up being sold to unsuspecting buyers.
TAGBASE solves both problems
Our browser extension brings trust and transparency to every transaction.
Verify physical Access
Sellers scan NFC tags embedded in products to create timestamped, location-verified proofs. Buyers can instantly see that the seller has the item in hand before purchasing.
Prove ownership
For products with blockchain-linked ownership tokens, sellers can cryptographically prove they're the rightful owner. No more stolen goods slipping through the cracks.
How it works
Three layers of verification to ensure trust in every transaction
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Rolex Submariner
Vintage 1985 Model
"random comment here"
ⓘ Claims are public. Compare details to verify relevance.
Physical Access verification
Sellers prove physical access to products by scanning NFC tags, creating timestamped verification records with location data.
Blockchain ownership
For products with blockchain integration, sellers can cryptographically prove they own the associated token on Cardano, Ethereum, Solana and more.
Wallet signing
Connect your wallet and sign a challenge message to prove you own the blockchain token linked to the product. Simple and secure.
The buyer-Seller verification flow
See how TAGBASE creates trust between strangers in secondary market transactions
Products with NFC tags
Products that have TAGBASE NFC tags can be verified using a smartphone. When scanned, the tag creates a timestamped verification record proving physical access to the item.
Optional Blockchain token
Some products have an associated blockchain token that represents ownership. If the seller holds this token in their wallet, they can cryptographically prove they are the rightful owner.
Buyer discovers a listing
A buyer finds an interesting product on any marketplace (eBay, Vinted, Facebook marketplace, etc.). They want to make sure the seller actually has the item and is the rightful owner before purchasing.
Buyer requests verification
The buyer contacts the seller and asks them to add a verification to the product listing URL. They may request a specific comment (e.g., "For john B.") to confirm it's a fresh verification made specifically for them.
Seller scans the NFC tag
The seller uses their smartphone to scan the NFC tag on the product. This creates a verification record linked to the marketplace listing URL, including the buyer's requested comment and an optional location.
Seller proves token ownership (Optional)
If the product has an associated blockchain token, the seller can connect their wallet and sign a message to prove they hold the ownership token. This adds an extra layer of trust.
Buyer verifies everything
The buyer revisits the listing URL and opens the TAGBASE browser extension. They can now see the fresh verification with their requested comment, the timestamp, location, and ownership proof if applicable. They can proceed with confidence!
Why this works
Timestamped records
Every verification is timestamped, so buyers can see exactly when the seller proved access, ensuring it's recent and relevant.
Custom comments
Buyers can request specific comments to verify the seller made the verification just for them, preventing reuse of old proofs.
Platform agnostic
Works on any website with any URL. The browser extension shows all verifications linked to the current page.
Bring trust to secondary markets
Install the TAGBASE browser extension and start verifying products on any marketplace.
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