The present disclosure provides a method for debugging of flash memory devices using NAND self-verification The method can include programming a selected page of the NAND flash memory device according to first and second programming data. The selected page can include a plurality of memory cells corresponding to a word line. The programming of the selected page can include a plurality of programming operations and a plurality of verifying operations. Ones of the plurality of verifying operations can be performed after corresponding ones of the plurality of programming operations to determine whether programmed memory cells of the selected page have threshold voltage levels according to the first or second programming data. The method can also include performing self-verification on the selected page to determine whether data stored at the selected page was overwritten and generating a fail indication upon determining that the data stored at the selected page was overwritten.