DigiDoc4 is an application for digitally signing and encrypting documents; the software includes functionality to manage Estonian ID-card - change pin codes etc.
Libdigidocpp library offers creating, signing and verification of digitally signed documents, according to XAdES and XML-DSIG standards. Documentation http://open-eid.github.io/libdigidocpp
Signature Verification Service
DEPRECATED DigiDoc3 Client is a program that can be used to sign digitally with ID-card and Mobile-ID, check the validity of digital signatures and open and save documents inside the signature container.