ViewerJS is the easiest way to add support for viewing presentations, spreadsheets, PDF's and other documents on your website or blog without any external dependencies. No tricks, no conversions, no unexpected downtime from external services, and no plugins required – it happens to work just fine in all major browsers today from the comfort of your own webserver.
ViewerJS is open source under the AGPL. KO GmbH provides consultancy, support and maintenance for applications that integrate ViewerJS.
WebODF is open source under the AGPL. KO GmbH licenses WebODF for commercial use as well and can provide consultancy, support and maintenance for applications that integrate WebODF.
WebODF is used, among others, in the ownCloud Documents application.