# List of online encyclopedias

This is a list of well-known online encyclopedias that are accessible or 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 have always existed online, such as Wikipedia.

## General reference

| Name | Language | Description | Status | Access | Content license | Fork of | Merged with |
| Wikipedia | Various (see list here) | General interest, wiki | Active | Free | CC BY-SA 4.0, GFDL | None | None |
| Nupedia | English | Combined with GNUpedia | Defunct | None | GFDL 1.1 or later | None | None |
| Interpedia | English | General interest, the first site to propose a free encyclopedia written by users | Defunct | None | Unknown | Free | None |
| Everipedia | English | General interest | Read-only (archived) | Free | CC BY 4.0 | Wikipedia | None |
| Citizendium | English | General interest, wiki | Active | Free, copyleft | CC BY NC SA 3.0 | None | None |
| Conservapedia | English | American conservative and Christian interests | Active | Free | Unknown | None | None |
| Scholarpedia | English | Articles are written by scholars and peer-reviewed for accuracy | Active | Free | CC BY NC SA 3.0 | None | None |
| Encyclopædia Britannica | English | General interest | Active | Limited free access and features, subscription for full access | Unknown | None | None |
| Baidu Baike | Chinese | Collaborative online encyclopedia hosted by the major Chinese search engine company Baidu | Active | Free | Unknown | None | None |
| Enciklopedio Kalblanda | Esperanto | General interest. The first online encyclopedia in Esperanto | Defunct | None | CC BY SA 3.0, GFDL | None | Esperanto Wikipedia |
| EcuRed | Spanish | General interest. Cuban | Active | Free | None | None | None |
| Encyclopedia.com | English | General interest | Active | Free | None | None | None |
| Baike.com | Chinese | General interest. China's largest wiki | Active | Free | Unknown | None | None |
| Brockhaus Enzyklopädie | German | General interest | Active | Limited free access and features, subscription for full access | Unknown | None | None |
| Columbia Encyclopedia | English | General interest | Active | Free | Unknown | None | None |
| Crnogorska Enciklopedija | Montenegrin | General interest (hopes to encourage a Montenegrin language Wikipedia) | Defunct | None | Unknown | None | None |
| Croatian Encyclopedia | Croatian | General and national encyclopedia | Active | Free | Unknown | None | None |
| Den Store Danske Encyklopædi | Danish | General interest | Active | Free | Unknown | None | None |
| Digital Universe | English | Collection of articles on educational, cultural, and scientific topics | Defunct | Free | Unknown | None | None |
| Doosan Encyclopedia | Korean | General interest | Active | Free | Unknown | None | None |
| Ekşi Sözlük | Turkish | General interest | Active | Free | Unknown | None | None |
| Encarta (1993–2009) | English | General interest | Defunct | None | Unknown | None | None |
| Enciclonet | Spanish | General interest | Active | Limited free access and features, subscription for full access | None | None | None |
| Encyclopædia Britannica 11th Edition (1910–11) | English | General interest | Defunct | Public domain: completely free access from several online sources | None | None | None |
| Encyclopedia of China | Chinese | General interest | Active | Subscription | Unknown | None | None |
| Từ điển bách khoa Việt Nam | Vietnamese | General interest. State-sponsored encyclopedia. | Active | Free | Unknown | None | None |
| Encyklopedia Internautica | Polish | General interest | Active | Free | Unknown | None | None |
| Enciclopedia Libre Universal en Español | Spanish | Fork of the Spanish Wikipedia, using wiki software, released under the GFDL | Defunct | Free, copyleft | Unknown | None | None |
| Encyclopædia Universalis | French | General interest encyclopedia published by Encyclopædia Britannica | Active | Subscription | Unknown | None | None |
| Everything2 | English | General interest, users can submit articles on the topic of essentially anything | Active | Free | None | None | None |
| The Free Dictionary | English, Spanish, German, French, Italian, Chinese, Portuguese, Dutch, Norwegian, Greek, Arabic, Polish, Turkish, Russian | TheFreeDictionary's Encyclopedia draws from various sources, including The Columbia Encyclopedia. | Active | Free | None | None | None |
| GNE | English | General interest articles are released under a GNU license. Formerly GNUpedia. | Defunct | None | Unknown | None | None |
| Gran Enciclopèdia Catalana | Catalan | General interest | Active | Free | Unknown | None | None |
| Grand Larousse encyclopédique | French | General interest | Active | Free | None | None | None |
| Great Norwegian Encyclopedia | Norwegian (Bokmål) | General interest | Active | Free | Unknown | None | None |
| Great Russian Encyclopedia | Russian | General interest | Active | Free | Unknown | None | None |
| Great Soviet Encyclopedia | Russian, English | General interest, often from the former official Soviet viewpoint. | Active | Free | Unknown | None | None |
| Hamichlol | Hebrew, English | General interest, designed for Haredim | Active | Free. Copyleft: mirror of Wikipedia content; copyright: original content. | Unknown | Wikipedia | None |
| Internetowa encyklopedia PWN | Polish | General interest | Active | Free | Unknown | None | None |
| Krugosvet (Rus. Кругосвет) | Russian | General interest. | Active | Free | Unknown | None | None |
| Marathi Vishwakosh | Marathi | General Interest | Active | Free | Unknown | None | None |
| Marefa | Arabic | General interest | Active | Free | Unknown | None | None |
| Mawdoo3 | Arabic | General interest | Active | Free | Unknown | None | None |
| Metapedia | Hungarian, German, English, Spanish, Swedish, Romanian, Estonian, French, Slovenian, Czech, Portuguese, Norwegian, Danish, Greek, Dutch | Far right-wing, white nationalist and neo nazi encyclopedia | Active | Free | Unknown | None | None |
| Meyers Konversations-Lexikon 4. ed. 1888 - 1892 | German | General interest | Defunct | access from several online sources | Unknown | None | None |
| Namuwiki | Korean | General interest | Active | Free | CC-BY-NC-SA 2.0 KR | Rigveda Wiki | None |
| Nationalencyklopedin | Swedish | General interest, comprehensive | Active | Subscription | Unknown | None | None |
| New World Encyclopedia | English | Project of the Unification movement | Active | Free. Wikipedia fork. | CC BY SA 3.0, GFDL | Wikipedia | None |
| Oeconomische Encyclopädie (1773-1858) | German | General interest | Defunct | Public domain: completely free access from several online sources | None | None | None |
| Oxford Bibliographies Online | English | | Active | Free | Unknown | None | None |
| Probert Encyclopaedia | English | General interest | Defunct | None | Unknown | None | None |
| Proleksis Encyclopedia | Croatian | General and national encyclopedia | Active | Free with registration | Unknown | None | None |
| Ruwiki | Russian | General interest, forked from Russian Wikipedia during the Russo-Ukrainian war | Active | Free | CC BY-SA 4.0 | Russian Wikipedia | None |
| Rigveda Wiki | Korean | General interest | Active | Free | CC-BY-NC-SA 2.0 KR | None | None |
| Sarvavijnanakosam | Malayalam | General interest | Active | Free | Unknown | None | None |
| Sogou Baike | Chinese | Collaborative online encyclopedia hosted by the major Chinese search engine company Sogou | Active | Free | Unknown | None | None |
| Superpedia | Indonesian, Sundanese, Javanese | General interest | Active | Free | Unknown | None | None |
| Susning.nu (2001–09) | Swedish | A Swedish language wiki | Defunct | None | Unknown | None | None |
| Tamil Encyclopedia | Tamil | General Interest | Active | Free | Unknown | None | None |
| Treccani | Italian | General interest | Active | Free | None | None | None |
| Veropedia | English, Dutch, Spanish | Mirrors stable versions of selected English Wikipedia articles | Defunct | None | Unknown | None | None |
| Visuotinė lietuvių enciklopedija | Lithuanian | General interest | Active | Free | Unknown | None | None |
| WIEM Encyklopedia | Polish | General interest | Active | Free | Unknown | None | None |
| Winkler Prins | Dutch | General interest, three different age levels | Active | Subscription | Unknown | None | None |
| World Book Encyclopedia | English | General interest | Active | Subscription | Unknown | None | None |
| Klexikon | German | General interest for children aged six to twelve years | Active | Free | CC BY-SA 3.0 | None | None |

## Biography

| Site | Language | Description | Access |
| Afro-American Encyclopaedia | English | Classic historical encyclopedia (1895) | Free |
| Australian Dictionary of Biography | English | Entries on notable Australians who have died | Free |
| Croatian Biographical Lexicon | Croatian | Multi-volume biographical reference work on notable figures from Croatian history | Free |
| Deutsche Biographie | German | Biographies on notable German speaking people | Free |
| American National Biography | English | Biographies of notable Americans | Subscription |
| Dictionary of Irish Architects | English | Biographical information on Irish architects from 1720 to 1940 | Free |
| Kdo byl kdo | Czech | Biographies on notable Czech and Slovak people | Free |
| Österreichisches Biographisches Lexikon 1815–1950 | German | Biographies on notable Austrians | Free |
| Oxford Dictionary of National Biography | English | Comprehensive 66-volume reference work on notable figures from British history | Subscription |
| Dictionary of New Zealand Biography | English, Māori | Entries on notable New Zealanders who have died | Free |
| Dizionario Biografico degli Italiani | Italian | Biographical Dictionary of Italian People, published by the Istituto dell'Enciclopedia Italiana Treccani | Free |

## Antiquities, arts, and literature

| Site | Language | Description | Access |
| Dictionary of Art Historians | English | Covers topics relating to art historians, art critics, and their dictionaries | Free |
| Dictionary of Greek and Roman Antiquities | English | Incorporates text from the 19th-century encyclopedia of the same name. Focuses on topics of cultural and historical Greek and Roman significance. | Free |
| Dictionary of Greek and Roman Biography and Mythology | English | Focuses on topics dealing with Greek and Roman mythology and people | Free |
| Dictionary of Greek and Roman Geography | English | Focuses on topics relating to Greek and Roman geography | Free |
| Enciclopedia Dantesca | Italian | Devoted to Dante Alighieri and his time, by the Istituto dell'Enciclopedia Italiana Treccani | Free |
| The Encyclopedia of Fantasy | English | | Free |
| Encyclopedia Mythica | English | Covers folklore, mythology, and religion. | Free |
| Harper's Dictionary of Classical Literature and Antiquities | English | Covers subjects of classical antiquity; text from 1898 | Free |
| The History of Nordic Women's Literature | English, Danish, Swedish | Searchable online English-language version including many biographies | Free |
| Kindlers Literatur Lexikon | German | Online-only since 2009, covers works and writers of world literature | Subscription |
| The Literary Encyclopedia | English | Literature related articles | Subscription |
| Oxford Art Online | English | Visual art; formerly Grove Art Online and The Dictionary of Art. Originally published in 1996 as a 34-volume printed encyclopedia; offered online since 1998. | Subscription |
| SIKART | English, German, French, Italian | Biographical dictionary and database of Swiss visual art | Free |

## Regional interest

| Site | Language | Description | Access |
| Agropedia | | Covers topics related to agriculture in India | |
| Austria-Forum | German, English | Online database of Austrian culture | Free |
| Banglapedia | Bengali, English | Bangladesh-related topics | Free |
| The Canadian Encyclopedia | English, French | General interest regarding Canada and Canadiana (original content of the hard copy Canadian Encyclopedia) | Free |
| Chalo Chatu | English | Collaborative online encyclopedia hosted by Chalo Chatu Foundation featuring comprehensive articles on Zambian culture and history, etc. | Free |
| Culinary Heritage of Switzerland | German, French, Italian, Romansh | Online encyclopedia of traditional Swiss cuisine and produce. | Free |
| DEDI | English, Slovene | Online encyclopedia of the natural and cultural heritage of Slovenia, operated by the Slovenian Academy of Sciences and Arts Scientific Research Center. | Free |
| Dictionary of Sydney | English | Articles on the history and culture of Sydney, Australia | Free |
| Encyclopaedia of Islam, 3rd edition | English | About the Islamic world, not a Muslim encyclopedia | Subscription |
| Encyclopædia Iranica | English, plans for a future Persian version | Topics on Iranology and the influence of the Iranian peoples throughout history | Free |
| The Encyclopaedia of Korea | English | Korea-related topics | Free |
| Encyclopedia of Korean Culture | Korean | Korea-related topics | Free |
| Encyclopedia Sindhiana | Sindhi | General interest regarding Sindh | Limited free access and features |
| Internet Encyclopedia of Ukraine | English | Ukraine, its history, people, geography, society, economy, and cultural heritage, based on the five-volume print Encyclopedia of Ukraine | Free |
| Gazetteer for Scotland | English | Articles on the geography and locations of Scotland | Free |
| Historical Dictionary of Switzerland | French, German and Italian | Articles on the history of Switzerland. | Free (without illustrations) |
| Kodansha Encyclopedia of Japan | English | Comprehensive articles on Japanese arts, culture, history, and politics, etc. | Subscription |
| Oslo byleksikon | Bokmål (Norwegian) | Online encyclopedia of Oslo, operated by the Society for Oslo Byes Vel, with an emphasis on places, buildings and historical events. | Free |
| Panyathai | Thai, limited English | General interest. Designed to honor the Thai king Bhumibol Adulyadej | Free |
| Sahapedia | English | Open encyclopedic resource on the arts, cultures, and histories of India. | Free |
| Te Ara: The Encyclopedia of New Zealand | English, Māori | Site operated by the New Zealand government regarding information about the country | Free |
| Vienna History Wiki | German | Articles on the history of the city of Vienna, Austria. Includes 31,000 entries from the 2nd edition of Historisches Lexikon Wien. | Free |
| Turkpidya | English, German, Danish, Spanish, French, Italian, Hungarian, Dutch, Portuguese, Romanian, Turkish, Croatian, Polish, Czech, Greek, Bulgarian, Russian, Serbian, Hebrew, Arabic, Persian, Japanese, and Korean. | Online encyclopedia about Turkey and Turkic Nations | Free |
| Unam Wiki | Korean | Wiki with stated South Korean conservative leanings. | Free |

### 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 |

## Pop culture and fiction

| Site | Language | Description | Access |
| Don Markstein's Toonopedia | English | Focuses on articles about print and animated cartoons | Free |
| The Encyclopedia of Science Fiction | English | Authors, books, films of sci-fi. | Free |
| Emojipedia | English | Emoji | Free |
| Fringepedia | English | Contains articles about the American television drama Fringe. | Free |
| h2g2 | English | Collection of sometimes humorous encyclopedia articles, based on Douglas Adams's The Hitchhiker's Guide to the Galaxy. | Free |
| Heroes Wiki | English, Dutch, French, German, Hebrew, Italian, Portuguese, Spanish, Swedish, Turkish | Contains articles pertaining to the American television drama Heroes. | Free |
| Know Your Meme | English | A website and video series which uses wiki software to document various Internet memes and other online phenomena, such as viral videos, image macros, catchphrases, and internet celebrities. | Free |
| Lostpedia | English, German, Spanish, French, Italian, Japanese, Dutch, Polish, Portuguese, Russian, Chinese | Contains articles pertaining to the hit drama Lost | Free |
| Memory Alpha | English, Bulgarian, Chinese, Czech, Dutch, Esperanto, French, German, Polish, Portuguese, Russian, Serbian, Spanish, Swedish | Articles about Star Trek | Free |
| LyricWiki (2006–20) | Multilingual | Wiki-based lyrics database and encyclopedia | Defunct |
| Pixiv Encyclopedia | Japanese | Japanese pop-culture encyclopedia | Free |
| The Rocklopedia Fakebandica | English | Articles on fake bands from popular entertainment | Free |
| Supernatural Wiki | English | Contains articles about the American television drama Supernatural. | Free |
| Tolkien Gateway | English | J.R.R. Tolkien-related articles | Free |
| TV Tropes | English, German, Esperanto, Spanish, French, Norwegian, Finnish, Swedish, Al Bhed, Quenya | Articles related to the devices and conventions that a fiction writer can reasonably rely on as being present in the audience members' minds and expectations | Free |
| Fallout Wiki | English, German, Spanish, Bulgarian, Finnish, French, Georgian, Hungarian, Italian, Japanese, Korean, Lithuanian, Dutch, Norwegian, Polish, Portuguese, Russian, Swedish, Turkish, Chinese | Fallout-related articles | Free |
| Wookieepedia | English, German, Spanish, Bulgarian, Danish, Finnish, French, Croatian, Hungarian, Italian, Japanese, Dutch, Norwegian, Polish, Portuguese, Russian, Romanian, Slovak, Slovene, Swedish, Turkish, Chinese | Star Wars-related articles | Free |
| Wowpedia / Warcraft Wiki | English, German, Spanish, French, Czech, Danish, Greek, Persian, Finnish, Hebrew, Hungarian, Icelandic, Italian, Lithuanian, Latvian, Dutch, Nynorsk, Bokmål, Polish, Portuguese, Brazilian Portuguese, Russian, Slovak, Korean, Japanese, Chinese | Warcraft-related articles | Free |

## Mathematics

| Site | Language | Description | Access |
| Encyclopedia of Mathematics | English | Encompasses articles on the topic of mathematics | Free |
| Encyclopedia of Triangle Centers | English | Information about ten thousands of triangle centers, including coordinates, operations, incidence, equations, etc. | Free |
| EqWorld | English, Russian | Articles on mathematical equations | Free |
| MathWorld | English | Articles on a wide variety of mathematics related topics | Free |
| On-Line Encyclopedia of Integer Sequences | English | Information about hundred thousands of integer sequences, including formulas, related sequences, programs, etc. | Free/CC BY-NC 3.0 |
| PlanetMath | English | Mathematics related topics and articles | Free/GNU |
| Stacks Project | English | A mathematics textbook writing project with the aim to cover "algebraic stacks and the algebraic geometry needed to define them" | Free |
| nLab | English | Category theory and related topics | Free |

## Media

| Site | Language | Description | Access |
| Bulgarian Rock Archives | Bulgarian | Archives of Bulgarian rock bands. | Free |
| Canadian Pop Music Encyclopedia | English | Encyclopedia of Canadian pop music | Free |
| Encyclopaedia Metallum | English | Archives of heavy metal bands | Free |
| Grove Music Online | English | Mostly on historic and classical music worldwide. It is the online version of The New Grove Dictionary of Music and Musicians, which has 20 printed volumes and was first published in 1980. | Subscription |
| IMDb | English, German, French, Hungarian, Italian, Polish, Portuguese, Romanian, Turkish, and Spanish | Information related to world films, television programs, home videos, video games, and internet streams | Free |
| MusicBrainz | English, German, French, Italian, Dutch | An open music encyclopedia that collects music metadata. | Free |
| MOOMA | Hebrew | Articles on Israeli music and musical artists | Free |
| PCGamingWiki | English | Covers PC gaming | Free |
| Rock in China | English | Documents and archives contemporary Chinese music, ranging from rock music to punk, metal, electro, jazz and hip-hop | Free |

## Philosophy

| Site | Language | Description | Access |
| Stanford Encyclopedia of Philosophy | English | Philosophy subjects | Free |
| Routledge Encyclopedia of Philosophy | English | Philosophy articles | Subscription |
| Internet Encyclopedia of Philosophy | English | Philosophy related articles | Free |
| Marxists Internet Archive | Multilingual | Topics related to the study of Marxism | Free |

## Politics, law, and history

| Site | Language | Description | Access |
| Ballotpedia | English | American politics, elections, and public policy | Free |
| The Concise Encyclopedia of Economics | English | Economics – part of the Library of Economics and Liberty. Edited by David R. Henderson | Free |
| Cyclopaedia of Political Science, Political Economy, and the Political History of the United States | English | Articles about science, economics, and American authors. The 1899 edition is available online | Free |
| Diplopedia | English | US State Department internal encyclopedic wiki, available for diplomats and overseas US agents to use | Access only through the State Department |
| dKosopedia | English | Political encyclopedia written from a progressive/liberal Democratic point of view | Free |
| Encyclopedia Titanica | English | Encyclopedia related to the building and sinking of the RMS Titanic | Free |
| Encyclopedia of World Problems and Human Potential | English | Presents articles on perceived human problems | Free |
| Gapminder | English | Historical global trends in health, poverty, and demographics | Free |
| glbtq.com | English | Gay, lesbian, bisexual, transgender, and queer culture. | Free |
| HistoryLink | English | Articles on the history of Washington state | Free |
| Holocaust Encyclopedia | English, Arabic, Persian, French, Spanish | Holocaust-related articles, published by the United States Holocaust Memorial Museum | Free |
| JurisPedia | Arabic, English, Chinese, French, German, Spanish, Dutch | An academic encyclopedia on the concepts of law | Free |
| Max Planck Encyclopedia of Public International Law | English | Encyclopedia on public International Law | Free |
| Online Encyclopedia of Mass Violence | French | Electronic database focusing on massacres and genocides of the 20th century. | Free |
| Our World in Data | English | Global trends on economic growth, poverty, health, war, violence, education, and demographics | Free |
| Spartacus Educational | English | | Free |
| World History Encyclopedia | English | The world's most-read history encyclopedia, covering world history from all time periods; reviewed by an editorial team, not a Wiki. | Free |

## Religion and theology

| Site | Language | Description | Access |
| AhmadiPedia | English | Dedicated to the study of the Worldwide Ahmadiyya Muslim Community. | Free, public domain |
| Catholic Encyclopedia | English | Topics relating to Catholicism, text from 1913 and 1922 | Free, public domain |
| Christian Cyclopedia | English | Collection of historical and theological information | Free |
| Easton's Bible Dictionary | English | Articles on Christianity and theology | Free, public domain |
| Encyclopaedia Biblica | English | Contains articles about "the Literary, Political and Religious History, the Archaeology, Geography, and Natural History of the Bible" | Free |
| Encyclopedia of Mormonism | English | Articles by Mormon academics on history and doctrine of the Church of Jesus Christ of Latter-day Saints (LDS Church). | Free |
| Global Anabaptist Mennonite Encyclopedia Online | English | Topics relating to Anabaptism and Mennonites | Free |
| İslâm Ansiklopedisi | Turkish | Articles on topics concerning Islamic studies. | Free |
| The Jewish Encyclopedia | English | Topics relating to Judaism | Free |
| Jewish Virtual Library | English | Portals to essential Jewish topics | Free |
| Encyclopedia Mythica | English | Covers folklore, mythology, and religion. | Free |
| Punjabipedia | Punjabi | Entries on Sikhism | Subscription |
| Schaff–Herzog Encyclopedia of Religious Knowledge | English | Christian, published 1908–1914 | Free, public domain |
| WikiShia | Various (see list here) | Shia Islam, published since 2013 | Free |

## Science and technology

| Site | Language | Description | Access |
| sv:Elephant Encyclopedia | English | Contains articles on the subject of elephants since 1995 | Free |
| Encyclopedia Astronautica | English | Contains articles on the subject of space exploration and astronomy, no longer updated since 2019 | Free |
| Encyclopedia of Earth | English | Articles on the Earth and its ecosystems | Free |
| Engineering and Technology History Wiki | English | The history of technology, a partnership between the United Engineering Foundation, and the AIChE, AIME, ASCE, ASME, IEEE, SPE, and SWE | Free |
| Free On-line Dictionary of Computing | English | Computing and related subjects | Free |
| Glottopedia | English | Linguistics | Free |
| Javapedia | English | Coverage of all topics related to the Java Platform | Free |
| Omniglot | English | Covers languages and writing systems. | Free |
| Proteopedia | English | Wiki-based 3D encyclopedia of proteins and other molecules. | Free |
| RP Photonics Encyclopedia | English | Laser technology, photonics, and various other areas of photonics such as nonlinear optics, non-laser light sources, fiber optics, and ultrashort pulses of light. | Free |
| ScienceWorld | English | Covers astronomy, scientific biography, chemistry, and physics. Like MathWorld, it is edited by Eric Weisstein. | Free |

### Life sciences

| Site | Language | Description | Access |
| Animal Diversity Web | English | Student wiki-type database at the University of Michigan of animal natural history, distribution, classification, and conservation biology. | Free |
| APpedia | Chinese | Contains articles on the subject of general animal protection | Free |
| ARKive | English | Visual and audio recordings of the world's species | Defunct |
| Encyclopedia of Life | English, French | Seeks to categorize all 1.8 million known species on the planet | Free |
| Encyclopedia of Life Sciences | English | Biology related articles | Subscription |
| Encyclopedia of Life Support Systems | English | Articles about the natural and social sciences | Subscription |
| Erowid | English | Information about psychoactive substances | Free |
| FishBase | English, Spanish, Portuguese, French, German, Italian, Dutch, Chinese (Simplified Han), Chinese (Traditional Han), Greek, Swedish, Russian, Persian, Vietnamese, Thai, Lao, Hindi, Bengali | Articles on fish species | Free |
| Flora Europaea | English | Covers different plant species | Free |
| King Abdullah Bin Abdulaziz Arabic Health Encyclopedia | Arabic, English | Health encyclopedia | Free |
| Palaeos | English | Covers palaeontology | Free |
| World Flora Online | English | Covers the world's plant species | Free |
| Wikispecies | English | Seeks to create a catalog of all living things | Free |
| ZipcodeZoo | English | Encyclopedia of all living things | Defunct |

### 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 |