Cello is an early, discontinued graphical web browser for Windows 3.1; it was developed by Thomas R. Bruce of the Legal Information Institute at Cornell Law School. It was released as shareware in 1993. While other browsers ran on various Unix machines, Cello was the first web browser for Microsoft Windows, using the winsock system to access the Internet. In addition to the basic Windows, Cello worked on Windows NT 3.5 and with small modifications on OS/2.

Cello was created because of a demand for Web access by lawyers, who were more likely to use Microsoft Windows than the Unix operating systems supporting earlier Web browsers, including the first release of Mosaic. The lack of a Windows browser meant many legal experts were unable to access legal information made available in hypertext on the World Wide Web. Cello was popular during 1993/1994, but fell out of favor following the release of Mosaic for Windows and Netscape, after which Cello development was abandoned.

Cello was first publicly released on 8 June 1993. A version 2.0 was announced, but development was abandoned. Version 1.01a, 16 April 1994, was the last public release. Since then, the Legal Information Institute at Cornell Law School has licensed the Cello 2.0 source code, which has been used to develop commercial software.

The browser is no longer available from its original homepage. However, it can still be downloaded from mirror sites.

The development of Cello started in 1992, with beta versions planned for June 1993 and a release for July 1993. It was publicly announced on 12 April 1993.

The Legal Information Institute at Cornell Law School created the first law site on the Internet in 1992 and the first legal website in 1993. However, at the time, there were no web browsers for the Microsoft Windows operating system, which was used by most lawyers. Thus, to allow lawyers to use their website, the Legal Information Institute developed the first Windows-based Web browser. This was made possible by a grant from the National Center for Automated Information Research.

Although other browsers at the time were based on CERN's WWW libraries called libwww, PCs of the time were not powerful enough to run the UNIX-oriented code. As a result, Thomas Bruce had to rewrite most of the WWW libraries to work on Microsoft Windows. Unlike most commercial browsers at that time, Cello used none of Mosaic's source code and thus had a different look and feel.

Steven Sinofsky, president of the Windows division at Microsoft wrote in a June 1994 email: We do not currently plan on any other client software [in the upcoming release of Windows 95], especially something like Mosaic or Cello. Nevertheless, on 11 January 1995, Microsoft announced that it had licensed the Mosaic technology from Spyglass, which it would use to create Internet Explorer. On 15 August 1995, Microsoft debuted its own web browser Internet Explorer 1 for Windows 95. While it did not ship with the original release of Windows 95, it shipped with Microsoft Plus! for Windows 95.