If you use bit.ly to shorten the links, pay attention, in their official blog they have just reported that a problem has occurred that may have jeopardized several accounts of its users.
If the access data to bitly accounts have been effectively stolen, we can be talking about a really huge problem, since many short custom domains used to send links to social networks use the bit.ly platform behind.
Although they do not confirm that the theft has occurred, they recommend the following steps:
1) Identify yourself in bitly.com and click on the Advanced section within Your Settings. 2) Click on the Reset link next to Legacy API key, to change the key used by the applications associated with our account. 3) Copy the new API key and change it in all applications that use our bit.ly (buffer, dlvr.it, etc.) This includes both publishing platforms and mobile applications and buttons for sharing social networks. 4) Go to the Profile section and change the password. 5) Disconnect and connect again any application that uses bitly, we can consult them in the Connected Accounts section within Your Settings.
At the moment they have not given more information about the problem, but we will keep you informed if the theft of the data is confirmed.