The National Science Foundation (NSF) is an US independent federal agency. The organisaition has an annual budget of about $6.9 billion. Most NSF grants awards to individuals or small groups of investigators who carry out research at their home campuses.
There are a large number of NSF grants and fellowships awarded each year. NSF fellowships are in seven directorates of the organisation:
Computer and Information Science and Engineering
Mathematical and Physical Sciences
Social, Behavioral and Economic Sciences
Deadlines of NSF grants and fellowships are varied. Contact person is in scholarship detail.
Make sure to keep an eye on this generous and awarding fellowships to keep updated with the closing ones in the field of your interest.