Never heard of credit sesame before. Is it free? As Amy mentioned before: “since 2009, consumers can’t buy their Experian FICOs and it is only available to lenders.” If credit sesame states that it’s an Experian FICO score, then I suppose they have a way of getting it, but I would double check just to make sure.
Having said that, Experian is one of the 3 major credit bureaus. I check my Experian score all the time, so I think it should be a pretty reliable score even if it’s not the Experian FICO.