Duotrope

Duotrope opened in 2005 as a free market database and went paid ($5/month) in 2013 amid community outcry it has long outlived. It tracks thousands of fiction, poetry, and nonfiction markets with data no one else has at scale: reported response times, acceptance rates, and "recent responses" fed by its users' submission logs.

Its weekly digests flag newly opened and closing markets, and its interviews archive is quietly excellent. The knock: listings depend on publisher self-reporting and user data, so coverage skews toward markets whose submitters use Duotrope. For a working poet running a serious submission operation, it remains the statistical backbone.