Salesforce Object Search Language (SOSL) includes new support for searching through list views.
REST API includes new, changed, and deprecated calls.
SOAP API includes new, changed, and deprecated calls.
Chatter REST API
Integrate mobile apps, intranet sites, and third-party web applications with Salesforce using Chatter REST API. Create draft posts, threaded comments, a folder’s share link, and managed content topics.
Reports and Dashboards REST API
These resources have new properties: Analytics Notifications (/analytics/notifications/notification_ID), Dashboards (/analytics/dashboards/), and Report Types (/analytics/report-types/).
User Interface API
Build Salesforce UI for native mobile apps and custom web apps using the same API that Salesforce uses to build Lightning Experience and Salesforce for Android, iOS, and mobile web. Now you can allow users to choose how much white space they prefer in their user interface.
Salesforce Console API
Open CTI API
The onNavigationChange() method is now invoked when users create a case record and the new case is viewed in the same tab. The methods to set softphone size in Lightning Experience have higher maximums.