Productivity adjacent discussions and communities are great places to strike up a conversation and find like-minded people that could benefit from your tool.

Asking how others are currently solving the problem your tool does is a good entryway. You can follow their answer with a suggestion to try your product if it sounds like it could be useful.

For more of a shotgun approach you can post on betalist, reddit /startups Share Your Startup thread, ShowHN, etc.