An apparatus, system, and method are disclosed for delivery of software. A snapshot module is included to create a snapshot of development software libraries still in a development phase, the development software libraries comprising substantially an entire replacement set of software code. A testing module is included to apply a set of tests to the snapshot to ensure that the snapshot is substantially free from defects and a delivery module delivers the snapshot to a user. The snapshot may be configured for a mainframe computer operating system such that a previous version of the software code is replaced in a single operation. The mainframe computer operating system may be the z/OS operating system.