https://techcrunch.com/2017/10/24/gmail-gets-third-party-add-ons/

Google is launching third-party add-ons for Gmail today. These native extensions will allow you to bring the power of services like Asana, DocuSign, Trello, Wrike and others directly to your inbox — no matter whether you are an enterprise or individual user.

If you’ve been following along, this announcement doesn’t come as a total surprise. The company first announced that this feature was coming at its I/O developer conference in March. At the time, though, this was only a developer preview and since then, Google worked with a number of partners to bring a first set of native extensions to Gmail.