KryptoKoder provides PDF digital signature solutions for developers.
MyPDFSigner is a command line tool and a set of language (PHP, Ruby and Python) modules to digitally sign PDF documents using tokens stored in a PKCS#11 security device (a smart card, like a citizen card issued by many governments in Europe, or a USB token) or a PKCS#12 file (a *.pfx or *.p12 file).
The command line tool is available for Windows, Mac OS X and Linux, while the scripting language modules are currently only available for Linux.
MyPDFSigner supports Time Stamping (RFC 3161), PAdES B-B, B-T and LTV (ETSI TS 103 172), eIDAS (EU regulation 910/2014), Encryption, Bulk Signing and Signature Verification . PDF documents signed by MyPDFSigner are correctly displayed by Adobe Reader.