The add-on can currently load most Office file types including doc, xls, ppt but also sxw, csv, rtd and several image formats. Don’t worry, it does not install an Office suite as a Firefox add-on. It makes use of various online services that can display and edit the aforementioned file types.

The add-on displays a configuration dialog after installation that allows the user to pick one out of four services for each file type. The default service for every file type is the Zoho Viewer which can be changed to Zoho Writer, Google Docs and Thinkfree Viewer.

The add-on is basically redirecting the file download to one of the online services so that it can be viewed and edited there. That’s definitely a clever concept.

Now seriously. Have you ever received a document (a clean one) with an extension you never heard of and didn’t even know what application you were supposed to use to open it? That’s not a problem any more due to applications and online services that can understand varied file formats and display the contents of those files for you. Of course, you can’t edit such files with viewers because their only purpose is to display the contents of the document. But hey, better that nothing, ain’t it…

Let me introduce 2 ways of viewing contents of a document with an unknown extension:

1) Install a single program to rule all the document extensions you can ever happen to meet (alright, maybe not absolutely all of them but pretty much most of the common ones). I’ve tried a freeware tool called TextMaker Viewer and it does it’s job well. It’s a simple document viewer without useless functions but it has everything needed to fulfil it’s purpose. It supports 10 of the most common file formats which should be quite enough for average use. According to the coders, Linux version is under development.

2) Don’t install anything while keeping the possibility to view common file types through your browser. Zoho Viewer is an online service that does just that. You can either choose a file from your local computer to be displayed or enter URL of an online document you’d like to read. You can even print the document or obtain a code allowing you to embed it somewhere else on the web. No annoying ads, clean interface, 15 file types supported.

The advantage of the second method is that you do not have to execute the file to view its contents.