1. A system comprising: one or more processors of one or more computing systems; and one or more memories with stored instructions of a conversion tool that, when executed by at least one of the one or more processors, configure the system to: receive a selection by a user of a source execution environment that is one of multiple source execution environments supported by the conversion tool; determine an interaction manner for the selected source execution environment that is one of multiple distinct interaction manners supported by the conversion tool for use in interacting with the multiple source execution environments, wherein the multiple distinct interaction manners supported by the conversion tool include interacting via multiple application programming interfaces (APIs) provided by the multiple source execution environments, and wherein the determining of the interaction manner for the selected source execution environment includes dynamically selecting a first API to use, wherein the first API is one of the multiple APIs that is provided by the selected source execution environment and that is different from other APIs of the multiple APIs not used by the selected source execution environment; interact with the selected source execution environment in the determined interaction manner to obtain data for a virtual machine program that is executable in the selected source execution environment, including performing programmatic interactions over one or more computer networks to use the first API; modify the obtained data to configure the virtual machine program to be executable in a destination execution environment that is distinct from the selected source execution environment; and provide the modified obtained data for use in executing the virtual machine program in the destination execution environment.