Inno Setup is a free installer for Windows programs. First introduced in 1997, Inno Setup today rivals and even surpasses many commercial installers in feature set and stability.

Key features:

• Support for all versions of Windows in use today: Vista, XP, 2008, 2003, 2000, Me, 98, 95, and NT 4.0. (No service packs are required.)
• Extensive support for installation of 64-bit applications on the 64-bit editions of Windows. Both the x64 and Itanium architectures are supported. (On the Itanium architecture, Service Pack 1 or later is required on Windows Server 2003 to install in 64-bit mode.)
• Supports creation of a single EXE to install your program for easy online distribution. Disk spanning is also supported.
• Standard Windows 2000/XP-style wizard interface.
• Customizable setup types, e.g. Full, Minimal, Custom.
• Complete uninstall capabilities.
• Installation of files: Includes integrated support for "deflate", bzip2, and 7-Zip LZMA file compression. The installer has the ability to compare file version info, replace in-use files, use shared file counting, register DLL/OCX's and type libraries, and install fonts.
• Creation of shortcuts anywhere, including in the Start Menu and on the desktop.
• Creation of registry and .INI entries.
• Integrated Pascal scripting engine.
• Support for multilingual installs.
• Support for passworded and encrypted installs.
• Silent install and uninstall.
• Full source code is available (Borland Delphi 2.0-5.0).