Inno Setup è un installation builder, ovvero un programma che consente di realizzare pacchetti di installazione. Grazie agli installer creati con Inno Setup è quindi possibile distribuire con più facilità il software, sollevando gli sviluppatori da tutte le problematiche relative alla fase di installazione delle applicazioni. Malgrado non sia distribuito sotto licenza GPL, Inno Setup è completamente gratuito e i sorgenti sono liberamente scaricabili.

Di seguito riportiamo un elenco sintetico delle principali caratteristiche di Inno Setup:

• Support for all versions of Windows in use today: 7, 2008 R2, 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.
• Running other programs before, during or after install.
• Support for multilingual installs, including right-to-left language support.
• Support for passworded and encrypted installs.
• Support for digitally signed installs and uninstalls.
• Silent install and uninstall.
• Unicode installs. (Windows 2000/XP or later)
• Integrated Pascal scripting engine option for advanced run-time install and uninstall customization.
• Full source code is available (Borland Delphi 2.0-5.0 and 2009).