Last month at its annual I/O event, Google launched the Gmail API, which helps developers build apps that work with Gmail.

Inbox works similarly, except it connects with all email providers, from AOL to Outlook, the company wrote in a press release. It allows developers to build tools to help users with email, like apps to autosend emails or time-delay messages. One unique feature is for a developer to access data in a user's mailbox. "For example, you could use Inbox to build an app showing detail from all the flight confirmation messages a user received last year," the startup's site explains.