slack.com
In short: Slack Marketplace (slack.com) accepts public slack app listing. It is free to submit, takes only a few minutes, and scores 86/100 on our impact ranking (high impact).
Build an your tool Slack app, enable public distribution, and submit it for review.
Must provide meaningful Slack functionality and meet security, OAuth, support, and UX rules.
Priority is high, which sets the band. It is free and quick to complete, which adjusts it within that band. The score ranks your queue — it is not a measure of domain authority.