Phantom OS is an orthogonally persistent managed code general-purpose operating system.

It is free and open-source software (FOSS) released under a GNU Lesser General Public License (LGPL).

Security is achieved by the absence of pointer arithmetic and the inability of an application to get linked to an object other than by calling a public method.

[2] Persistence – Application code does not see OS restarts and can live forever—this does not use the concept of a file and any variable or data structure can be stored forever and at the same time be available directly through a pointer.

[1] Two ways to migrate code are offered:[2] As of October 2019[update], the system exists as an alpha version for x86 IA-32 processors.