From March 30th 2018, Google is turning off support for goo.gl. If you visit the goo.gl website you will see the notification. If you have been using the goo.gl URL shortener services then you should really look out for other alternatives.
Google is shutting down goo.gl, from 30th March 2018, the support for goo.gl will be turned off and from 13th April 2018, only existing users will be able to create short links on the goo.gl website. They can view analytics day / download short link info in CSV format.
However do note the goo.gl will discontinue after 30th March 2019. The notification also mentions that the previously created links by users will redirect to the intended destinations. So if you had created short link on goo.gl, you don’t have to worry about that links, it will still work, even after 30th March 2019.
This Google URL Shortener services were rolled out in 2009. The reason why Google is shutting down the goo.gl services is that there are many popular URL shortening services and most of these are now integrated in the respective app / pages etc. For example Facebook and Twitter they have their built in URL shortening.
So google will be turning down support for goo.gl and replacing with Firebase Dynamic Links also called FDLs. These are smart URLs for more info check this page.