Electronic Filing System of the United States Patent and Trademark Office (USPTO), also referred to as EFS-Web or simply EFS, was a web-based system for submitting patent applications and related documents electronically.
§ 111(a), utility patent reissues, U.S. National Stage applications under 35 U.S.C.
§ 371, ASCII text files (for sequence listings, computer listings, mega tables, mathematical formulae, chemical formulae, and 3D protein crystal structures), and petitions under 37 C.F.R.
After filing via EFS, users were sent an electronic receipt that acknowledges the submission date.
EFS was retired after November 8, 2023, in favor of the USPTO Patent Center.