Picocli is a modern framework for building powerful, user-friendly, GraalVM-enabled command line apps with ease. It supports colors, autocompletion, subcommands, and more. In 1 source file so apps can include as source & avoid adding a dependency. Written in Java, usable from Groovy, Kotlin, Scala, etc.
A header-only C++ argument parser library. Supposed to be flexible and powerful, and attempts to be compatible with the functionality of the Python standard argparse library (though not necessarily the API).