In http://bitcoinwhoswho.com/ , we can find wallet name from bitcoin address, how do they do so? Is there any signature of wallet name in bitcoin address or in transaction id?
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I have had a quick look at the website you referenced specifically, however, it suggests most of the information that they have is because people have 'claimed' their address and provided the details.
If you have a look at this example, that represents just about all that is publicly obtainable when someone makes a transaction + the public keys. And, website information, names and, labels is not sourced from the blockchain.