European Patent Office (EPO):  
www.epo.org [1]

US Patent and Trademark Office (USPTO): 
www.uspto.gov [2]

World Intellectual Property Organization WIPO: 
www.wipo.int [3]

African Regional Intellectual Property Organization (ARIPO):
www.aripo.org [4]

Euro-Asian Patent Office:
www.eapo.org [5]

German Patent and Trademark Office:
www.dpma.de [6]

Japanese Patent Office: 
www.jpo.go.jp [7]

Korean Patent Office:
www.kipo.go.kr [8]

Indian Patent Office:
www.ipindia.nic.in [9]

Chinese Patent Office:
www.sipo.gov.cn [10]

French Patent Office:
www.inpi.fr [11]

Russian Patent Office:
www.rupto.ru [12]

British Patent Office:
www.ipo.gov.uk [13]

Italian Patent Office:
www.uibm.gov.it [14]

Hong Kong Patent Office:
info.gov.hk [15]

Netherlands Patent Office:
www.octrooicentrum.nl [16]

Swiss Patent Office: 
www.ige.ch [17]