The National Science Foundation has a search page that includes the contact information for Research Experiences for Undergraduates summer research programs. You will need to contact the specific program for application information. Additionally, programs may submit their specific application information for publishing in the list below.
PathwaysToScience.org has a searchable database of 600+ summer research programs for undergraduates in all STEM disciplines. These are all fully funded opportunities including programs sponsored by NSF, NASA, NIH, etc. They also have a selection of resources to help you strengthen your applications.
The opportunities below have been submitted to CUR for display.