A copy of a federal DD-214 form cannot be printed online. The request form necessary to procure a copy of a DD-214 can be found online at the National Archives (Archives.gov).
The DD-214 form is a military discharge form. Officially, the certificate of release of discharge from active duty, the DD-214 is a federal form which provides details of military service and certifies the bearer's eligibility for military benefits.
A copy can be obtained by filling out the SF-180, which is a request pertaining to military documents. This document requires a dated signature and must be either mailed or faxed to the National Archives office.