Twitter already lets you do it, now Google will be allowing users to download their online Gmail and Google Calendar data, for backup or transfer purposes.
Google has said that users will be able to “…download all of your mail and calendars or choose a subset of labels and calendars. You can also download a single archive file for multiple products with a copy of your Gmail, Calendar, Google+, YouTube, Drive, and other Google data.”
The rollout isn’t immediate, but access to Google Calendar downloads should live for everyone immediately. Gmail downloads will gradually become available over the course of the next month.