HK91.com
Offers information on Heckler and Koch firearms, a message board, and gun rights data.

Heckler and Koch USA, Inc.
Features this North American subsidiary which also distributes Fabarms.

Mark23 Owners Guild
Presents a library of information on everything for owners and enthusiasts of the Mark23 or Mk23mod0 SOCOM.

Chris's Unofficial H&K P7 Website
Offers information about the P7 series of semiauto pistols made by Heckler and Koch with an HK-4 annex.

HKPro.com
Features this unofficial resource for the serious student of Heckler and Koch. Provides a forum and also sells HKPro gear.