
The Astrophysics Data System (ADS) is an online database of over eight million astronomy and physics papers from both peer reviewed and non-peer reviewed sources. Abstracts are available free online for almost all articles, and full scanned articles are available in Graphics Interchange Format (GIF) and Portable Document Format (PDF) for older articles. It was developed by the National Aeronautics and Space Administration (NASA), and is managed by the Harvard–Smithsonian Center for Astrophysics.

The Biodiversity Heritage Library (BHL) is a consortium of natural history and botanical libraries that cooperate to digitize and make accessible the legacy literature of biodiversity held in their collections and to make that literature available for open access and responsible use as a part of a global "biodiversity commons". The BHL consortium works with the international taxonomic community, rights holders, and other interested parties to ensure that this biodiversity heritage is made available to a global audience through open access principles. In partnership with the Internet Archive and through local digitization efforts, the BHL has digitized millions of pages of taxonomic literature, representing tens of thousands of titles and more than 100,000 volumes.

The Biodiversity Heritage Library for Europe (BHL-Europe) was a three-year (2009–2012) EU project aimed to the coordination of digitization of literature on biodiversity. It involved 28 major natural history museums, botanical gardens, libraries and other European institutions. BHL-Europe was founded in Berlin in May 2009 and regarded itself as a European partner project of the Biodiversity Heritage Library (BHL) project, which was founded in 2005 and initially formed by ten United States and British libraries.

The Chinese Text Project is a digital library project that assembles collections of early Chinese texts. The name of the project in Chinese literally means "The Chinese Philosophical Book Digitization Project", showing its focus on books related to Chinese philosophy. It aims at providing accessible and accurate versions of a wide range of texts, particularly those relating to Chinese philosophy, and the site is credited with providing one of the most comprehensive and accurate collections of classical Chinese texts on the Internet, as well as being one of the most useful textual databases for scholars of early Chinese texts.

The Choral Public Domain Library (CPDL) is a sheet music archive which focuses on choral and vocal music in the public domain or otherwise freely available for printing and performing.

The Cochrane Library is a collection of databases in medicine and other healthcare specialties provided by Cochrane and other organizations. At its core is the collection of Cochrane Reviews, a database of systematic reviews and meta-analyses which summarize and interpret the results of medical research. The Cochrane Library aims to make the results of well-conducted controlled trials readily available and is a key resource in evidence-based medicine.
The Complete Work of Charles Darwin Online is a freely-accessible website containing the complete print and manuscript works of Charles Darwin, as well as related supplementary material.

The David Rumsey Historical Map Collection is one of the world's largest private map collections. It has over 150,000 maps and cartographic items. The collection was created by David Rumsey who, after making his fortune in real estate, focused initially on collecting 18th- and 19th century maps of North and South America, as this era "saw the rise of modern cartography."

Dryad is an international open-access repository of research data, especially data underlying scientific and medical publications. Dryad is a curated general-purpose repository that makes data discoverable, freely reusable, and citable. The scientific, educational, and charitable mission of Dryad is to provide the infrastructure for and promote the re-use of scholarly research data.

EconBiz is an academic search portal for journals, working papers, and conferences in business studies and economics. It is provided by the ZBW - German National Library of Economics, Leibniz Information Centre for Economics. The portal was started in 2002 as the Virtual Library for Economics and Business Studies.

The Education Resources Information Center (ERIC) is an online digital library of education research and information. ERIC is sponsored by the Institute of Education Sciences of the United States Department of Education.

The eGranary Digital Library is a product of the WiderNet Project, a non-profit aimed at providing access to information technology and library services in developing countries.

The EServer was an open access electronic publishing cooperative, founded in 1990, which published writings in the arts and humanities free of charge to Internet readers. In 2006, it was rated by Alexa as the most popular arts and humanities website in the world.

EuroDocs: Online Sources for European History is a digital history portal that offers links to online facsimiles, transcriptions, and translations of European primary historical sources. The sponsoring organization is the Harold B. Lee Library at Brigham Young University, where it was begun in 1995 by Richard Hacken, European Studies Bibliographer.

Fragmentarium is an online database to collect and collate fragments of medieval manuscripts making them available to researchers, collectors and historians worldwide. It is an international collaboration of major libraries and collections including the British Library, Bibliothèque nationale de France, Martin Schøyen Collection, Bavarian State Library, Harvard, Yale and the Vatican. It is based in Switzerland and the project's current director is Professor Christoph Flüeler from the University of Fribourg and the Virtual Manuscript Library, Switzerland.

The Internet Library Sub-saharan Africa (ilissAfrica) is a German Internet portal that offers an integrated access to relevant scientific information resources in the field of African Studies and the region Africa South of the Sahara. ilissAfrica covers social sciences, history, philology, ethnology and cultural studies. The website is presented in German, English and French.

The International Music Score Library Project (IMSLP), also known as the Petrucci Music Library after publisher Ottaviano Petrucci, is a subscription-based project for the creation of a virtual library of public-domain music scores. Since its launch on February 16, 2006, over 495,000 scores and 59,000 recordings for over 152,000 works by over 18,000 composers have been uploaded. Based on the wiki principle, the project uses MediaWiki software, with an iOS app released July 10, 2018 and an Android app released March 28, 2019. Since June 6, 2010, the IMSLP also includes public domain and licensed recordings in its scope, to allow for study by ear.

The Live Music Archive (LMA), part of the Internet Archive, is an ad-free collection of over 170,000 concert recordings in lossless audio formats. The songs are also downloadable or playable in lossy formats such as Ogg Vorbis or MP3. The website is known for its extensive collection of Grateful Dead recordings, and contains music from many other bands.

Marxists Internet Archive is a non-profit online encyclopedia that hosts a multilingual library of the works of communist, anarchist, and socialist writers, such as Karl Marx, Friedrich Engels, Vladimir Lenin, Leon Trotsky, Rosa Luxemburg, Che Guevara, Mikhail Bakunin, and Pierre-Joseph Proudhon, as well as that of writers of related ideologies, and even unrelated ones. The collection is maintained by volunteers, and is based on a collection of documents that were distributed by email and newsgroups, later collected into a single gopher site in 1993. It contains over 180,000 documents from over 850 authors in 80 languages.

The Matheson Trust is an educational charity based in London dedicated to further and disseminate the study of comparative religion, especially from the point of view of the underlying harmony of the major religious and philosophical traditions of the world.

New Advent is a website that provides online versions of various works connected with the Catholic Church.

SABDA or SABDA Bible Software is an Indonesian integrated Bible study platform that's based on the Online Bible engine, with multilingual Bibles available in the program.

textfiles.com is a website dedicated to preserving the digital documents that contain the history of the bulletin board system (BBS) world and various subcultures, and thus providing "a glimpse into the history of writers and artists bound by the 128 characters that the American Standard Code for Information Interchange (ASCII) allowed them". The site categorizes and stores thousands of text files, primarily from the 1980s, but also contains some older files and some that were created well into the 1990s. A broad range of topics is presented, including anarchy, art, carding, computers, drugs, ezines, freemasonry, games, hacking, phreaking, politics, piracy, sex and UFOs. The site was created and is run by Jason Scott.

The Old School Emulation Center (TOSEC) is a retrocomputing initiative founded in February 2000 initially for the renaming and cataloging of software files intended for use in emulators, that later extended their work to the cataloging and preservation of also applications, firmware, device drivers, games, operating systems, magazines and magazine cover disks, comic books, product box art, videos of advertisements and training, related TV series and more. The catalogs provide an overview and cryptographic identification of media that allows for automatic integrity checking and renaming of files, checking for the completeness of software collections and more, using management utilities like ClrMamePro.