[abhink]

You normally get a blue card with a period of validity, which is normally 4 years. While the blue card is valid you can freely switch between organisations within EU. The only restriction is that you cannot change the field of your work. So a software engineer can only apply for other software engineering positions.

To get a blue card you primarily need an unlimited contract. Companies do help with the process of procurement, like setting up an appointment. Once you get your blue card you also get another "green slip" that mentions your current employer along with your job role. Anytime you move to a different job, this slip needs to be updated, which is then done by your new employer.