DigiSigner is a free tool for viewing and digitally signing portable document format (PDF) files. DigiSigner tool is free for both private and commercial use.DigiSigner is capable of viewing PDF documents and creating digital signatures in them using X.509 certificates. The tool supports and manages certificates from file key stores (PFX/PKCS#12), smartcards, USB sticks (PKCS#11) and internal Microsoft Windows key store. Support of time stamp servers is provided.