CollabOffice is implemented in javascript and uses HTML5 canvas for drawing documents. It uses only opensource technologies with business-friendly licenses. Since there is no free suitable collaborative libraries on the net, we have implemented our own approach, so documents are synchronized between users without delay or heavy traffic. Compared to other online editors, we use DOCX format for inner representation of the document. This allows to avoid implementing from/to DOCX convertors and even edit documents without server. Server is implemented in nodejs and also supports conversion to PDF.