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Research Guides

Searching for Patents by Keyword(s)


  • No controlled vocabulary in patents

  • Patents have the aspects of both a technical and a legal document

USPTO Website:  ability to search with keywords from 1976 to the present ONLY


Patent Search Databases (open access):

  • United States Patent & Trademark Office (USPTO)

    • 2 patent databases:  Patent Grants & Patent Applications -
    • USPTO Patent Search Portal (Search for Patents)
    • PubWest, PubEast:  Online search tools only available in the Public Search Room @ the USPTO and @ some PTRCs
  • Google Patents: Indexes full-text patent documents from the US, European Patent Office, Canada, China, Germany, and WIPO.

  • Free Patents Online (FPO IP Research & Communities)
    FreePatentsOnline (FPO) provides a free patent search database.  They also provide patent analysis software and other patent data services (for a fee).  The patent search database includes US patents and US patent applications as well as documents from the European Patent Office, WIPO, Japan and Germany.
  • Patent Lens
  • European Patent Office (EPO):  Espacenet
    Covers millions of patent documents from more than 90+ countries including the United States. Database of the European Patent Office (EPO)


Database with Patent Content (UW Subscription):

Additional USPTO Resources & Databases

Public PAIR (Patent Application Information Retrieval)
The U.S. Patent & Trademark Office Public PAIR system includes status, maintenance fee and file history information for United States patents. PDF images of some documents included. Online ordering of patent documents is available.

Search Published Sequences:  Issued and published sequences, tables and other mega items.

Search Patent Assignments:  Ownership information/Changes in ownership.

Main Patent Portal @ USPTO

Resources and Guidance:  Policies, procedures, guides, tools and manuals associated with the patent process.

Official Gazette for Patents (OG)


Outline: Searching for Patents by Subject

  • As far back in time as necessary

    • Cannot re-patent an identical invention

  • US Classifications and Subclassifications / CPC Classifications (Schemes/Schedules & Classification Symbols)

    • Also known as classes and subclasses in USPC (some continue to use this terminology in CPC)

    • USPC = US Patent Classification / CPC = Cooperative Patent Classification

  • Brainstorm terms - consider synonyms.  Use these terms to locate CPC schemes and classification symbols.  Use these terms to locate USPC classes and subclasses if needed.

  • Seven Step Strategy.

  • Browse CPC Classifications.

  • Search classification schemes by keywords or look up particular CPC symbols on the USPTO Classification Resources page.

  • USPTO database:  search by US class/subclass and CPC symbols 1790 to the present

    • CPC used for new Utility patent documents (2015-).  USPC still used to classify Design and Plant patent documents.

  • Examples of other search types:  Inventor (Patentee), Assignee (Owner), Issue Date, Attorney

  • Interpret results via patent titles, abstracts, full-text (process of elimination)

  • In a patentability search, people are hoping NOT to find something.  Searching for the absence of something?


UW Engineering Library Patent Searching Guide

Seven Step Strategy - Conducting a preliminary patent search (Handout - Long version)

Patent Classification Page (USPTO)

Index to the United States Patent Classification (USPC)

Cooperative Patent Classification (CPC)

Transition to a new patent classification system:  the CPC - Cooperative Patent Classification (USPTO and EPO informational site).

"The Cooperative Patent Classification (CPC) effort is a joint partnership between the United States Patent and Trademark Office (USPTO) and the European Patent Office (EPO) where the Offices have agreed to harmonize their existing classification systems (European Classification (ECLA) and United States Patent Classification (USPC) respectively) and migrate towards a common classification scheme."

Search Classification Systems (USPTO)  - CPC and USPC

Browse CPC Schemes (USPTO)

CPC Search and Browse by CPC Section (EPO)