Intellipedia is an online system for collaborative data sharing used by the United States Intelligence Community (IC). It was established as a pilot project in late 2005 and formally announced in April 2006. Intellipedia consists of three wikis running on the separate JWICS (Intellipedia-TS), SIPRNet (Intellipedia-S), and DNI-U (Intellipedia-U) networks. The levels of classification allowed for information on the three wikis are Top Secret Sensitive Compartmented Information (TS SCI), Secret (S), and Sensitive But Unclassified (SBU or FOUO) information, respectively. Each of the wikis is used by individuals with appropriate clearances from the 18 agencies of the IC and other national-security related organizations, including Combatant Commands and other federal departments. The wikis are not open to the public.

Intellipedia is a project of the Office of the Director of National Intelligence (ODNI) Intelligence Community Enterprise Services (ICES) office headquartered in Fort Meade, Maryland. It includes information on the regions, people, and issues of interest to the communities using its host networks. Intellipedia uses MediaWiki, the same software used by the Wikipedia free-content encyclopedia project. In contrast to Wikipedia, its intelligence analogue encourages editing that incorporates personal points of view regardless of rank as it was decided that, "much of the self-corrective knowledge in the Intelligence Community resides in personal points of view," and that "not all good ideas originate at the top."

The Secret version connected to SIPRNet serves the personnel of the Departments of Defense and of State, many of whom do not use the Top Secret JWICS network on a day-to-day basis. Users on unclassified networks can access Intellipedia from remote terminals outside their workspaces via a VPN, in addition to their normal workstations. Open Source Intelligence (OSINT) users share information on the unclassified Intelink-U wiki.

Intellipedia was created to share information on difficult subjects facing U.S. intelligence and to bring cutting-edge technology into its workforce. It also allows information to be assembled and reviewed by a variety of sources and agencies in order to address concerns that pre-war intelligence did not include robust dissenting opinions on Iraq's alleged weapons programs. A number of projects are underway to explore the use of Intellipedia for the creation of traditional Intelligence Community products. In the summer of 2006, Intellipedia was the main collaboration tool in constructing a National Intelligence Estimate on Nigeria.

Intellipedia was at least partially inspired by a paper written for the Galileo Award (an essay competition set up by the CIA and later taken over by the DNI), which encouraged any employee at any intelligence agency to submit new ideas to improve information sharing. The first essay selected was by Calvin Andrus, chief technology officer of the Center for Mission Innovation at the CIA, entitled "The Wiki and the Blog: Toward a Complex Adaptive Intelligence Community". Andrus' essay argued that the power of the Internet had come from the boom in self-publishing, and noted how Wikipedia's open-door policy allowed it to cover new subjects quickly.

The original version was developed in beta form in late 2004 by technologists at the Defense Intelligence Agency, adapting MediaWiki open-source software for deployment on the DIA-managed JWICS SCI network. In 2005 DIA officials arranged to transfer the software and content to community-wide management under ODNI auspices, to increase the system's utility and comprehensiveness. Richard A. Russell, Deputy Assistant Director of National Intelligence for Information Sharing Customer Outreach (ISCO) said it was created so "analysts in different agencies that work X or Y can go in and see what other people are doing on subject X or Y and add in their two cents worth or documents that they have. What we are after here is 'decision superiority', not 'information superiority.'"

In 2007, after sixteen months of being available across the entire community, it was noted by officials that the top-secret version of Intellipedia alone (hosted on JWICS) had 29,255 articles, with an average of 114 new articles and more than 6,000 article edits added each workday.

As of 2009, the overall Intellipedia project hosted 900,000 pages edited by 100,000 users, with 5,000 page edits per day. As of 2014, Intellipedia contained around 269,000 articles with the Top Secret Intellipedia counting 113,000 content pages with 255,000 users.