Viewer.JS combines a number of excellent open source tools that are built on HTML and javascript. Viewer.JS was funded by NLnet foundation and developed by KO GmbH.
The heavy lifting in Viewer.JS is done by these awesome projects:
WebODF is a JavaScript library created by KO GmbH. It was started by Jos van den Oever at KO and is now developed by a growing team including external collaborators. It makes it easy to add Open Document Format (ODF) support to your website and to your mobile or desktop applications. It uses HTML and CSS to display ODF documents.
PDF.js is a library created by Andreas Gal and others at Mozilla Labs. It is an HTML5 technology experiment that explores building a faithful and efficient Portable Document Format (PDF) renderer without native code assistance.
You can find additional information, some usage guides, and live examples at the project homepage.
Viewer.JS is a Free Software project. All code is available under the AGPL.
If you are interested in using Viewer.JS in your commercial product (and do not want to disclose your sources / obey AGPL), contact KO GmbH for a commercial license.