Some archives and special collections have digitized documents in their collections making them accessible to researchers around the world. Below are a few open digital archives with collections focused on the World War II era.
HathiTrust Digital Library is a digital preservation repository and highly functional access platform. HathiTrust provides long-term preservation and access services to digitized content from a variety of sources, including Google, the Internet Archive, Microsoft, and in-house member institution initiatives. Items in the public domain are in full-view for everyone and items held in copyright are searchable.
The British National Archives have made available digital copies of the Cabinet Papers. Organized into themes to help with searching topic coverage includes diplomacy and foreign affairs, economy and infrastructure, and society and welfare of the state.
A selection of documents, facsimiles, and transcriptions of materials covering history in Europe. Arranged by nation and then organized by period of time (where possible).
Diplomatic and professional papers of George S. Messersmith (1883-1960). The papers include extensive discussions of political and economic matters regarding Europe during the 1930s and Latin America in the 1940s and 1950s.
The American Presidency Project is a collection of presidential documents including speeches, memoranda, written statements, letters, etc. Can search by president to locate only documents relating to that presidency.