Are there any interest-free loans for online business? And how can I benefit from it?

SBA has low interest loans for small businesses. Interest rates are so low right now that whether or not you pay interest is almost of no concern. SBA is a govt sponsored program to help small buz develop.

http://www.investsafe.com/loans.html

http://www.sba.gov/

No, all loans accrue interest - it's how lenders make their money, (and are then able to loan out money to the next borrower). You may be able to find an interest-only loan/line of credit, where you only pay interest each month and then the principal balance is due at maturity. These types of loans are usually only for one year. The interest rate you receive will depend on many factors, including the type of business loan, collateral, personal & business income & debt, etc.