See https://github.com/rustyrussell/runes for a simpler alternative and implementation (this has C and Python, but there's also a Rust implementation because why not?)
However, the "no db access" property has proven to be untenable in practice. Users end up wanting to see what runes are issued, blacklist them, know when they were last used, and have rate limits. The last two are a killer, requiring some state to be kept (unless your system allows you to return a modified rune to the user, which is a different workflow from normal bearer creds).
