Povlsomware Ransomware is an open source ransomware available on github. It is written in C# and claims to test the "ransomware protection claims" by Anti-malware / security solutions.

Zeoticus is offline ransomware with no external dependencies and works on all Windows Operation Systems including Windows XP. It uses X25519 + XSalsa20 + Poly1305 for asymmetric encryption and Xchacha20 for symmetric encryption.

Vovalex Ransomware is written in D programming language, one of the unique features of this malware. Other thing about it like encrypting files and demanding ransom is same.

Namaste Ransomware is a rip off of Avaddon Ransomware. After encrypting user data it ask to goto https://sellix.io/product/600dc38dbf44c and Buy decryption Key.

SunCrypt ransomware encrypts data from large companies, business users and educational institutions, and then ask them to go ransomware site to learn how to pay the ransom in BTC and get the files back.