After years of being treated like the backwater of productivity apps by tech giants, calendars are suddenly hot. Both Microsoft and Google are investing in the space, recognizing that calendars hold a rich trove of data that will help build personalized services like suggesting a restaurant for a meeting or hailing a ride to your next event.

Google will soon release a calendar app for iOS, its first release of a standalone calendar specifically for the platform, according to a person briefed on the matter. That follows a recent update of Google calendar for Android that reworked its design and integrated better with Gmail but has drawn criticism for eliminating older features, like the ability to view events a month at a time.

Meanwhile, Microsoft two weeks ago paid more than $100 million for calendar startup Sunrise, which pulls together relationship data with features like the ability to connect on LinkedIn directly from a calendar invite. The deal complemented Microsoft’s acquisition of email startup Accompli in December, both part of an effort to improve Microsoft’s mobile app presence. The Redmond giant doesn’t want to lose any more customers to Google’s productivity apps as it transitions Office customers to mobile and cloud versions of its cornerstone suite.