hackmd.io
In short: HackMD (hackmd.io) accepts public technical note. It is free to submit, takes a moderate amount of preparation, and scores 66/100 on our impact ranking (useful).
Create a substantive public tutorial or implementation note that uses your tool and includes a contextual source/product link.
Public notes must provide original useful content; avoid duplicated marketing copy and disclose affiliation where appropriate.
Priority is medium, which sets the band. It is free and moderate to complete, which adjusts it within that band. The score ranks your queue — it is not a measure of domain authority.