Nearly 930,000 files containing about 13 million pages are available after a long-running freedom of information campaign.
Files include spoon-bending experiments at the University of Edinburgh, an attack at the US consulate and communist sympathiser rallies all dating back to the 1980s.
Several pieces of research from the university’s para-psychic department was kept by the CIA under its Stargate programme into the paranormal.
They include a paper by leading parapsychologist Deborah Delanoy in which she exposes a teenage metal-bending fraudster in 1983-84.
Her subject, Tim, was a “bright and very affable” 17-year-old who the research team deemed to be an ideal subject.
“Tim claimed to have started bending metal, mostly cutlery, at the age of four and to have been doing so ever since,” reads Ms Delanoy’s report kept by the CIA.
After seven-and-a-half months of laboratory tests, researchers began to suspect Tim was a fraud and used a hidden camera to expose him.
The report says: “Tim confessed to deceptive behaviour. Her said that he was a practicing magician who had wished to see if it were possible for a magician to pose successfully as a psychic in a laboratory.”
The primary lesson of the research, Ms Delanoy documents, was that “we must never let ourselves forget that our subjects may be deceiving us”.
Other University of Edinburgh papers kept by the CIA relate to extrasensory perception - or experiences not explained by known physical or biological understanding. A university spokesman said: “We conduct research into a wide range of areas and it’s understandable major global institutions take an interest in it.”
The Stargate programme has long fascinated conspiracy theorists and is widely credited for influencing the 2004 book by Jon Ronson, The Men Who Stare at Goats.
In the book, made into a movie in 2009 starring George Clooney and Ewan McGregor, US special forces attempt to harness paranormal powers as a weapon.
Edinburgh psychologist Drew McAdam said the CIA’s interest in the paranormal is well-documented.
He said: “They [the CIA] were interested in anything because they got information that the Russians were into it. It was a case of if they’re doing it, we should be doing it.”
“I’m not a dyed in the wool sceptic,” says McAdam. “Just because they don’t understand it, people label it psychic but it’s just stuff the human mind can do.”
Stargate memos reveal how Gueller was able to partly replicate pictures drawn in another room.
The CIA previously only released its historical declassified records to be viewed in person at its archives in Maryland.
A campaign to have the files released online took more than two years and went to, often, farcical extremes.
non-profit freedom of information group, MuckRock, sued the CIA to force it to upload the collection.
While journalist Mike Best crowd-funded more than £12,000 to visit the archives and print out and then publicly upload the records, one by one.
“By printing out and scanning the documents at CIA expense, I was able to begin making them freely available to the public and to give the agency a financial incentive to simply put the database online,” Best blogged.
The released documents date back to the 1940s and include the papers of Henry Kissinger, secretary of state under presidents Richard Nixon and Gerald Ford.
Papers also include reported UFO sightings and recipes for invisible ink - as well as CIA research, development and operations.
Documents were also kept on Nazi war crimes while internal letters refer to the Watergate scandal that brought down President Nixon in the 1970s.
The global release of the files has pricked the interest of conspiracy theorists, the media and academics around the world.
The Washington Post reported how the files expose the “grim details” of the CIA’s post September 11 interrogation programme.
They document how one terror suspect died in Afghanistan in 2002 after being “doused with water and chained to a concrete floor as temperatures plunged below freezing,” reports the paper.
“Moving these documents online highlights the CIA’s commitment to increasing the accessibility of declassified records to the public,” said Joseph Lambert, CIA Director of Information Management.
“Access to this historically significant collection is no longer limited by geography. The American public can access these documents from the comfort of their homes.”