Ask: Is your side project definition override with the work that you do at job?
I am crm developer. I want to develop small fun crm project. But, I am also develop crm at my job also? Does this make problem in anyway? It really depends on the company you work for. Are they a private company, selling the CRM you work on? Regardless, I suggest talking with your company about working on the side. Believe me, it's worth keeping it all out in the open (Unless you want to compete with them, then figure out what code belongs to them), there have been horror stories about companies slurping up any work their devs do on the side, because of some verbiage on your agreement with them. Talk through with your company and find where the line is drawn, that will be your best bet. Is it possible if I do customization of opensource CRM ? Then I need permission ?