Q: I want to add timestamps when adding digital signatures to PDF documents in PDF Studio. Do you have a list of timestamp servers available?

A: We added support for SHA512 algorithm for communication with timestamp servers in version 2020.  This FreeTSA – Guide recommends using SHA-512. SHA-512 is part of SHA-2 (read more on md5hashing.net).

Below is the list of timestamp servers that we found working:

Timestamp Server SHA512
PDF Studio 2021+
https://freetsa.org/tsr SHA512
http://tsatest1.digistamp.com/tsa (requires authentication) SHA512
http://time.certum.pl SHA512
http://timestamp.digicert.com SHA512
http://zeitstempel.dfn.de SHA512 (Must increase padding length to 8000)
http://timestamp.apple.com/ts01 SHA512
http://timestamp.entrust.net/TSS/RFC3161sha2TS SHA512
http://tsa.cesnet.cz:3161/tsa SHA512
https://tsa.cesnet.cz:3162/tsa SHA512
http://tsa.cesnet.cz:5816/tsa SHA512
https://tsa.cesnet.cz:5817/tsa SHA512