What food is commonly sold today that might be similar to hardtack?

Hardtack (or hard tack) is a simple type of biscuit or cracker, made from flour, water, and sometimes salt. Hardtack is inexpensive and long-lasting. It is used for sustenance in the absence of perishable foods, commonly during long sea voyages, land migrations, and military campaigns.

A cracker is similar to a hardtack