That all depends on your level of employment stability, credit rating, savings, debt to income ratio, monthly and annual income (verified by tax returns, etc.). As little as 3.5% up to 35% down payment may be required by a lender finance a purchase for you.
Sometimes, there may be distressed sellers that may be willing to hold the note. If they own the property outright free and clear, with no mortgage, they may be willing to work a no money down deal, but higher monthly payments. Creativity can always help but if you have no down payment you must be sure you have great credit and a good, steady income.
All the best,