diff --git a/README.md b/README.md
index 45d06a9..9dd432e 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,9 @@
 
 A cli using https://github.com/mozilla/authenticator-rs
 
+Hard U2F projects:
+* https://github.com/google/OpenSK
+
 Soft U2F projects:
 * https://github.com/github/SoftU2F
 * https://github.com/SoftU2F/SoftU2F-Win