The SIFT patent has expired

April 4th, 2019

As of March 7th of this year, the SIFT patent has expired in the U.S.

U.S. patents are valid for 20 years from the earliest filing date, and SIFT (US6711293B1) was filed on 1999-03-08.

This means that usage of the SIFT algorithm no longer requires a license for use.

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