generally lookup the IPs (dig <hostname>) and then attempt a host/whois on that IP. For PushBullet it's hidden by CloudFlare so hard to see easily, you should try and find an exposed endpoint (which they haven't if they've done well).
https://chrome.google.com/webstore/detail/ipvfoo/ecanpcehffn...
(There's a right-click option to look up each address on bgp.he.net, but that doesn't happen automatically, for privacy.)