There are currently no versions of PaintTool SAI designed for platforms besides Windows. The developer stated that there is no plan to port the software to Macintosh and has released no statement regarding Linux development. Alternatives include MyBrushes Paint for Mac or the cross-platform options MyPaint and Krita.
Other options include installing Windows as a secondary operating system on a machine or using desktop virtualization software to run Windows within another operating system. Another alternative is WineHQ, which is a free, open-source, cross-platform software that allows users to install and run Windows-based software. The last version of PaintTool SAI reported to be stable using WineHQ was version 1.0.1. The current version is 1.2.0, for which there are no reports.