My research on how to import email addresses from users' contacts lists and quickly became a search for the best 3rd party solution for it. It would be ridiculous to implement oauth for a couple dozen email providers so you can hook into your user's contact lists. So after an afternoon of research and tinkering around I decided on and set up CloudSponge. Their setup docs are pretty straight forward so it was easy to get working in my Rails/React app. Using the finished product after an afternoon of researching/tinkering was definitely the best part.

The customer service team and the tech team over at CS have been great in helping us implement this software. Very responsive

We first started using Cloudsponge several years ago. Since the initial setup we haven't had any issues with it and it continues to run month after month. It saved us lots of development time compared to writing our own code to import from Google, Yahoo, AOL, etc. As our business has grown, so has our customer's usage of Cloudsponge to load their contacts into our site. We're now averaging over 1,000 address book imports a month and we almost never get questions about how to use the widget. We recently upgraded to the new Cloudsponge widget and the timimg was great. Their new widget UI has a mobile first design and works perfectly on our new mobile friendly site.