The article doesn't really describe how they came to choose those two formats. What about gzip, bzip2, tar, 7z, etc.?

(I tried uploading a tgz file and it doesn't appear to work).

The comment at the end ("We're always adding more file types to the Google Docs Viewer") suggests that these types may be considered at some point, but seems like once the infrastructure is there you get most other compression formats for free (assuming they're calling a server-side process to do the extraction rather than either reading the header themselves in javascript or rolling their own uncompression in their backend language without calling out).

> The article doesn't really describe how they came to choose those two formats.

I'd guess it's because they're the most common file compression formats? The formats you mentioned are pretty obscure to most mainstream users.

.tar.gz is not that uncommon, I would say. And once you have .tar.gz, support for .tar.bz2 is trivial to add.

And I would say that if you are attempting to open an archive on Google Docs Viewer, it's probably an archive of documents, and I would say that almost all archives of documents are in .zip or .rar.

>.tar.gz is not that uncommon, I would say.

On Unix, as tar has been built-in to Unix for decades.

And therefore OSX.

It is uncommon to the regular user, though, who is probably the one targeted by this feature.

Doesn't mention if it handles nested zips, and if it can visualize files with jar/war extensions (which are just zip files).

from the linked post - "ZIP and RAR archives that are embedded inside other archives also work. For example, if you have a RAR file inside a ZIP file (like in our example above) you can just click on that file to access the embedded archive. "

7-zip gets no love.