Google Patents Public Datasets
Google Patents Public Datasets is one of the most comprehensive and diverse patent search resources available. It brings together over 120M patent documents from more than one hundred patent offices around the world, covering applications, pre-grant publications, and granted patents.
You access it through BigQuery, Google's cloud data warehouse, where you can run SQL queries across the whole collection. Over 341M USPTO events are queryable, including the back-and-forth office actions between applicants and examiners, which makes it useful for studying how patents move through examination.
The data itself is free under CC BY 4.0, but running queries in BigQuery incurs Google Cloud compute costs, so budget for that if you plan to process large volumes.
Related sources
EPO Espacenet & Open Patent Services
Free access to over 140M patent documents from the European Patent Office (EPO). Its Open Patent Services text analysis tools have made patent full texts much easier to reach, though the terms are open access rather than an open reuse licence.
Harvard USPTO Patent Dataset (HUPD)
A large-scale, structured corpus of US patent applications built specifically for machine learning and natural language processing research. It fills the gap left by mainstream patent search tools, which are not designed with the ML and NLP community in mind.
PatentsView
A platform from the US Patent and Trademark Office (USPTO) for exploring US patent data, with visualisation and analysis tools. It connects patents, inventors, organisations, and locations in a regularly updated database, and offers both an API and complete bulk data tables.
WIPO PATENTSCOPE
A search service for international patent collections, maintained by the World Intellectual Property Organization (WIPO). It lets you search across patent applications filed under international treaties alongside national collections from many countries.