- Digital Public Library of America – The Digital Public Library of America brings together the riches of America’s libraries, archives, and museums, and makes them freely available to the world. It strives to contain the full breadth of human expression, from the written word, to works of art and culture, to records of America’s heritage, to the efforts and data of science.
- Discord – Social media.
- DoSomething.org – Founded in 1993, DoSomething.org is the largest not-for-profit exclusively for young people and social change. Join in the movement and help build connected, healthy, and sustainable communities.
- Down for everyone or just me? – Enter the address of a website and check if the website in question is down for everyone, or if it is just your computer.
- Dr. Lingua – Practice your hiragana/katakana skills here.
- Dropbox – Free online storage.