List of online encyclopedias
This is a list of well-known online encyclopedias that are currently accessible or were formerly accessible on the Internet.
The largest online encyclopedias are general reference works, though there are also many specialized ones. Some online encyclopedias are editions of a print encyclopedia, such as Encyclopædia Britannica, whereas others originated online, such as Wikipedia. Some online encyclopedia use Wikipedia's MediaWiki software or even fork Wikipedia content to create an alternative version.
Regional interest
US-specific
| Site | Language | Description | Access |
| 64 Parishes | English | Online encyclopedia of Louisiana, run by the Louisiana Endowment for the Humanities. | Free |
| Encyclopedia of Alabama | English | Encyclopedia covering the state of Alabama, sponsored by the Alabama Humanities Foundation. | Free |
| Encyclopedia of Appalachia | English | Dedicated to the region, people, culture, history, and geography of Appalachia. | Defunct |
| Encyclopedia of Arkansas | English | Project of the Central Arkansas Library System and is the only U.S. state encyclopedia sponsored by a public library | Free |
| Encyclopedia of Chicago | English | Free | |
| Encyclopedia Virginia | English | Encyclopedia funded by the Virginia Foundation for the Humanities and Library of Virginia, covering topics on Virginia | Free |
| Handbook of Texas | English | Articles on the U.S. State of Texas | Free |
| HistoryLink | English | Articles about Washington state history | Free |
| MNopedia | English | Online encyclopedia about Minnesota, published by the Minnesota Historical Society. | Free |
| NCPedia | English | Encyclopedia coordinated and managed by the North Carolina Government and State Library of North Carolina, covering a broad spectrum of topics and resources about North Carolina. | Free |
| New Georgia Encyclopedia | English | Articles on the U.S. state Georgia | Free |
| The Oregon Encyclopedia | English | Articles about Oregon | Free |
| Tennessee Encyclopedia | English | Covers the state of Tennessee | Free |
Philosophy
Science and technology
Medical
| Site | Language | Description | Access |
| Ganfyd | English | Online medical wiki | Defunct |
| Radiopaedia | English | Articles on medical imaging used in radiology and radiography | Free |
| WikEM | English | An emergency medicine open-access source | Free |