For curiosity, use it is acceptable but use it with Tor connection. Security wise.
It's not worth it using it even with Tor. If you input one address, then you won't give away any information, but check two or more addresses and the owner of the site can assume that they belong to the same owner and they can build a database of wallets with addresses that were previously unconnected.
To be safe you need to make a new Tor connection after every request and disable Javascript.