I wrote the MongoDB viewer (Ok, I wasn't very original with the name) to help me check document entries while working on the ossAccounts project.
I even put it on SourceForge more for completeness than ever expecting anyone to download it.
However, I am pleasantly surprised to find it now has over 200 downloads. How many are actually using the system I don't know but at least I've not had anyone complaining (yet).
While it is pretty basic (it is a dev tool after all) it more or less does the job it was designed for.
Hopefully this latest release will address the only issue I am aware of, namely that it would fail to display a documents data if a field held a null value (which is quite easy to do in MongoDB).
In a fit of enthusiasm I have even raised its Trove entry to Beta (from Alpha).
(Information about the MongoDBViewer can be found here).
