L'instal·lador de Debian, també conegut com «d-i», és el programari per instal·lar un sistema bàsic i funcional de Debian. Hi ha suport per a una àmplia gamma de maquinari, com ara dispositius encastats, portàtils, escriptoris i maquines de servidors, i s'ofereix un gran conjunt de programari lliure per a molts propòsits.
The installation is conducted by answering a basic set of questions. Also available are an expert mode that allows to control every aspect of the installation and an advanced feature to perform automated installations. The installed system can be used as is or further customized. The installation can be performed from a multitude of sources: USB, CD/DVD/Blu-Ray or the network. The installer supports localized installations in more than 80 languages.
The installer has its origin in the boot-floppies project, and it was first mentioned by Joey Hess in 2000. Since then the installation system has been continuously developed by volunteers improving and adding more features.