Microsoft Office Online

Microsoft Office Online (or Office for the web, Office on the web, and formerly Office Web Apps) is a free lightweight web version of Microsoft Office, which allows users to create and edit files using browser-based versions of Word, Excel, PowerPoint, OneNote, OneDrive, Outlook.com, Forms, People, Skype, and Sway. The basic online apps only include the necessary features and can be accessed for free through any Microsoft Account. Premium cloud-based features can be unlocked with a Microsoft 365 subscription.

Word, Excel, and PowerPoint on the web can all natively open, edit, and save Office Open XML files (docx, xlsx, pptx) as well as OpenDocument files (odt, ods, odp). Older Office file formats (doc, xls, ppt) are also able to be opened, but will be converted to the newer Open XML formats if the user wishes to edit them online. Password encrypted files cannot be opened in Office Online, nor can it open certain file types such as CSV in Excel or HTML in Word.

History
The online suite previously also included Flow and To Do. Users could install the on-premises version of this service, called Office Web Apps Server, in private clouds in conjunction with Microsoft SharePoint, Microsoft Exchange Server and Microsoft Lync Server.