Windows 8 Developer Preview, as Microsoft called the pre-beta build, was posted to a company website shortly after 8 p.m. Eastern on Tuesday.
The downloads, which range from 2.8GB to 4.8GB in size, come with no restrictions, a company spokeswoman confirmed earlier in the day.
Microsoft gave customers their at the new operating system during a two-and-a-half-hour presentation at its BUILD Windows conference, which opened Tuesday and runs through Friday.
When debuted a similar developers preview of in October 2008, the company limited the early look to attendees at its Professional Developers Conference (PDC), and told the general public to wait for a beta early the next year.
Within hours, the to online file-sharing sites.