In the computer industry, vaporware (or vapourware) is a product, typically computer hardware or software, that is announced to the general public but is late or never actually manufactured nor officially cancelled. Use of the word has broadened to include products such as automobiles.

Vaporware is often announced months or years before its purported release, with few details about its development being released. Developers have been accused of intentionally promoting vaporware to keep customers from switching to competing products that offer more features. Network World magazine called vaporware an "epidemic" in 1989 and blamed the press for not investigating if developers' claims were true. Seven major companies issued a report in 1990 saying that they felt vaporware had hurt the industry's credibility. The United States accused several companies of announcing vaporware early enough to violate antitrust laws, but few have been found guilty.

"Vaporware" was coined by a Microsoft engineer in 1982 to describe the company's Xenix operating system and first appeared in print in a newsletter by entrepreneur Esther Dyson in 1983. It became popular among writers in the industry as a way to describe products they felt took too long to be released. InfoWorld magazine editor Stewart Alsop helped popularize it by lampooning Bill Gates with a Golden Vaporware award for the late release of his company's first version of Windows in 1985.

Vaporware first implied intentional fraud when it was applied to the Ovation office suite in 1983; the suite's demonstration was well received by the press, but the product was never released.