Should I share source code when bidding a project

[travelbiz]

I had a web application designed last year and I am now seeking a new developer to make some minor changes and tweaks to the system (I did not like working with the original developer). I have reached out to a few freelancers and one of them has asked for all the source code in order to provide an estimate. Is that normal? I am not familiar with the process of hiring a developer for a new project, much less to update an existing set of code. My company invested a lot of money into having this code created and it is a tool that provides us a definite competitive advantage in our industry and it seems a little generous to offer it up in its entirety to another developer just to get their bid. What stops that designer from keeping a copy and offering it up as his own creation in the future? Am I being overly cautious here? Is there normally a confidentiality agreement that goes along with something like this? Also, any other tips you can offer a novice regarding hiring a developer to make updates to my program would be greatly appreciated.

[is_numeric]

The code is not the real issue here its the concept.
You have to just hope you get a trustworthy developer

I am assuming you are paying market rates for a contractor? if so, you have the right to ask them to work at your location. This doesn't stop them copying the code of course.