The best alternatives to Riviera Build are Keygen, Materia, and Applivery. If these 3 options don't work for you, we've listed a few more alternatives below.
Keygen is a powerful licensing service for desktop apps, on-premise software and other digital products written in C#, Swift, Java, C++, Kotlin, Node and more.
A domain-specific smart contract programming language for modeling, automating, and enforcing multi-party agreements. DAML contracts can run on multiple DLT/blockchain platforms.