A confidentiality agreement is one thing and is acceptable. One of the worst mistakes I ever made was to sign an agreement (on resigning from a company) saying

A confidentiality agreement is one thing and is acceptable. One of the worst mistakes I ever made was to sign an agreement (on resigning from a company) saying I would never criticize the company or its officers. It’s amazing what lawyers can do to make pretty much anything you say about such a company “criticism.” To this day all I can say is that I worked at the company, not that I resigned, not why I resigned, not what I learned. It has lead to some extremely uncomfortably situations with potential employers and investors even many years later.