Gmail is about to get a lot more flexible as Google has announced that "Add-ons" will be rolled out to the email service by the end of the year.
Currently available in the form of a developer preview, Google claims that these "Add-ons" will be built in App Scripts using a newly-designed "Card" system that allows developers to combine different UI components. On top of that, developers would only need to build their integration once as these add-ons would run natively on both the web version of Gmail as well as the Android and iOS Gmail app.
In terms of execution, the add-ons for Gmail appear to function much like add-ons for Google’s other apps such as Docs. For the web version of Gmail, clicking on an installed add-on will cause said add-on to appear on the right hand side of the screen. For Android and iOS devices, these Add-ons will open a new window on their devices. Furthermore, users will only need to install these add-ons once before being able to access them across the web and mobile device platforms.
As Add-ons for Gmail is currently in development, there are only three functional add-ons available for those who have access to the developer preview. The first is "Intuit QuickBooks", an add-on that lets users generate and send invoices, as well as confirms invoice status from Gmail.
The second is "ProsperWork", an add-on that checks the contact info of people on email threads against the information stored in their Customer Relationship Management (CRM) system. The third is "Salesforce", an add-on that lets users look up existing contacts, add new ones, and associate email threads with one or more existing opportunities in Salesforce.
No timeline has been given as to when Add-on for Gmail will be going live, but Google has mentioned that all Gmail users will be able to install Add-ons through the G Suite Marketplace later this year.