A link to NSF due dates can be found here: https://www.nsf.gov/funding/pgm_list.jsp?org=NSF&ord=date

NIH Deadlines:

Deadlines for Competing Grant and Cooperative Agreement Applications can be found on the NIH web site https://grants.nih.gov/grants/how-to-apply-application-guide/due-dates-and-submission-policies/due-dates.htm. Also, refer to the funding opportunity announcements for deadline information as not all applications are due on standard deadlines.

For additional funding opportunities, visit the Office of Proposal Development webpage.