Useful patent links

Open Patent Server (OPS) - Authentication

Open Patent Server (OPS)
EPO fair use charter
Registration page

Patent databases

Espacenet - The free, online EPO database
European Publication Server - The primary source of information on published EP patent applications and granted EP patents
Depatisnet - Electronic patent document archive of the DPMA, with roughly 80 million patent documents worldwide
Patent Electronic Business Center (USPTO) - Search tool for US patents and published applications
Swissreg - Swiss register of patents (including SPC), trademarks, designs and topographies
Patentscope - WIPO search tool for international patent applications

Online services

European Patent Register (Epoline) - Online european patent register and online public file inspection
Patent Center - Information regarding US patent application status
Trilateral CCD - Common Citation Document (CCD) application by the Trilateral Offices

Classification

International patent classification (IPC)
Cooperative patent classification (CPC)
United States patent classification (USPC)
F-Terms & FI classification (Japanese classification)
FI/IPC concordance search

Patent offices and institutions

European Patent Office (EPO)
World Intellectual Property Organisation (WIPO)
Patent offices of EPO member states
Patent offices outside the EPO

Other useful information

EPO Coverage - Useful tables and statistics, coverage and codes
List of kind codes
Glossary of patent terms