Shareware is a type of proprietary software that is initially shared by the owner for trial use at little or no cost. Often the software has limited functionality or incomplete documentation until the user sends payment to the software developer. Shareware is often offered as a download from a website or on a compact disc included with a magazine. Shareware differs from freeware, which is fully-featured software distributed at no cost to the user but without source code being made available; and free and open-source software, in which the source code is freely available for anyone to inspect and alter.

There are many types of shareware and, while they may not require an initial up-front payment, many are intended to generate revenue in one way or another. Some limit use to personal non-commercial purposes only, with purchase of a license required for use in a business enterprise. The software itself may be time-limited, or it may remind the user that payment would be appreciated.