Well, cligen is pretty mature/featureful, less work to use and well maintained and is the most common recommendation in Nim. If you happen to like more verbosely specified CLI interfaces like Python's argparse there are at least two pretty close to the Python argparse -- therapist [1] and nim-argparse [2]. There is much more to any programming language than its stdlib. { If you find these insufficiently "drop-in compatible", well, you can write your own port of argparse.py that is closer. :-) That is probably a good exercise. }

[1] https://maxgrenderjones.bitbucket.io/therapist/latest/therap...

[2] https://www.iffycan.com/nim-argparse/argparse.html