Which itr form is applicable for me?

Hi Experts, I am totally a newbie when it comes to Tax. I have a small business related to software. Its not a registered company or firm etc. I am working as a freelancer. I get my payments from US clients directly in to my bank account. I don't have any other source of income. I don't have any house or property or loan. I would like to know which ITR form is applicable for me to fill my income tax return? Thank You for your help.