Used in production in all my products and some companies.

• Parse command-line arguments, environment variables, and configuration values all together.
• Self-documenting parsers for correct-by-construction documentation
• Best-in-class command-line autocompletion
• Best-in-class errors
• Formatter-friendly API

• Parsing
  • Argument: progname hello
  • Option: progname --file foo.txt
    • Long Option: progname --file foo.txt
    • Short Option: progname --file foo.txt
    • Equals-version of long option: progname --file=foo.txt
    • Shorthand-version of short option: progname -ffoo.txt
  • Switch: progname --verbose
    • Long switch: progname --verbose
    • Short switch: progname -v
• Documentation
  • --help
    • Global --help page
    • Per-command --help page
  • Generated --version command
  • Generated manpage
• Completion
  • Bash completion
  • Zsh completion
  • Fish completion
• Static settings check

The example application contains a fully worked example.

This example is part of the build in CI so you can rely on it being up-to-date.