A few of my co-workers were asking me how I keep finding bugs in the server side validation, when they can’t reproduce the error at all via the GUI layer. What I told them was about a plugin I use(there are many more similar to this) called TamperData.
TamperData is a free plugin that allows you to monitor,intercept and transform HTML posts after they have been posted by your browser. This will allow you to see how your data is being sent, and override any client side validations that you were imposing.
Below are a few screen shots on the free plugin. You can download it here.