The following links refer to the project suport pages of the different blockchains. These homepages are owned and manged by the development community to support the open source projects for the specific blockchains. These pages also provide background information and links to the most recent reference wallet implementations and their release notes.
Bitcoin - Bitcoin Project homepage
Bitcoin Cash - Bitcoin Cash homepage
Litecoin - Litecoin Project homepage
Ethereum- Ethereum community homepage funded by the Ethereum Foundation
Stellar Lumen - Stellar Development Foundation