microsoft.com
In short: Microsoft Marketplace (microsoft.com) accepts public saas/appsource offer. It is free to submit, takes a moderate amount of preparation, and scores 98/100 on our impact ranking (highest impact).
Register in Partner Center and publish an your tool SaaS or Microsoft-integrated offer.
Requires an eligible Partner Center account, offer configuration, testing, and certification.
Priority is do first, 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.