The StreamJsonRpc library offers JSON-RPC 2.0 over any .NET Stream, WebSocket, or Pipe. With bonus support for request cancellation, client proxy generation, and more.
DnsClientX is an async C# library for DNS over UDP, TCP, HTTPS (DoH), and TLS (DoT). It also has a PowerShell module that can be used to query DNS records. It provides a simple way to query DNS records using multiple DNS providers. It supports multiple DNS record types and parallel queries.
.NET Community Toolkit is a collection of helpers and APIs that work for all .NET developers and are agnostic of any specific UI platform. The toolkit is maintained and published by Microsoft, and part of the .NET Foundation.
MailMergeLib is a mail message client library which provides comfortable mail merge capabilities for text, inline images and attachments, as well as good throughput and fault tolerance for sending mail messages.