Yes, with the EU Blue Card, changing jobs is easier than with almost any other residence permit for gainful employment. If you have a Blue Card and change your job, you do not even need permission from the immigration authorities. According to § Section 82 (1) sentence 6 AufenthG you only have the obligation to inform the immigration authority about your change. To comply with this obligation, it is best to send the authority the notice of termination from your old job, the employment contract for your new job, including a detailed job description, and a declaration of employment completed by your new employer. The obligation to notify applies only within the first yearin which you are employed with your EU Blue Card. After that, you are no longer obliged to notify a change of job. A change in your place of work does not cause the year does not start anew.
Within the first year of your employment with the EU Blue Card, the immigration authority can suspend your planned job change and reject it within 30 days of the suspensionif the new job does not fulfill all requirements of the Blue Card requirements. In this case, instead of the Blue Card, you may be issued a another residence permit for example a residence permit for skilled workers with an academic education in accordance with § 18b AufenthG.
At the end of the first year rejection of your change of employment by the foreigners authority is no longer possible - even if your new job does not meet all the requirements, for example because your new salary is below the salary threshold is below the salary threshold. Your Blue Card will still be valid for the entire period for which it was originally issued. However, an extension beyond this period could be problematic.