VMware provides several public API and Software Development Kits (SDK) products. You can use these products to interact with the following areas:
- host configuration, virtualization management and performance monitoring (vSphere Web Services API provides the basis for VMware management tools - available through the vSphere Web Services SDK). VMware provides language-specific SDKs (vSphere SDKs for Perl, .NET, or Java)
- server hardware health monitoring and storage management (CIM interface compatible with the CIM SMASH specification, storage management through CIM SMI-S and OEM/IHV packaged CIM implementations)
- extending the vSphere Client GUI (vSphere Client Plug-In API)
- access and manipulation of virtual storage - VMware Virtual Disk Development Kit (VDDK with library of C functions and example apps in C++)
- obtaining statistics from the guest operating system of a virtual machine (vSphere Guest SDK is a read-only programmatic interface for monitoring virtual machine statistics)
- scripting and automating common administrative tasks (CLIs that allow you to create scripts to automate common administrative tasks. The vSphere CLI is available for Linux and Microsoft Windows and provides a basic set of administrative commands. vSphere PowerCLI is available on Microsoft Windows and has over 200 commonly-used administrative commands.

Details Here: https://communities.vmware.com/community/vmtn/developer/

vMA is a Linux-based virtual machine that is pre-installed with a command-line interface and select third-party agents needed to manage your vSphere infrastructure. Administrators and developers can use vMA to run scripts and agents to manage vSphere 5.5, vSphere 5.1 and later, vSphere 5.0 and later systems. vMA includes the vSphere SDK for Perl and the vSphere Command-Line Interface (vSphere CLI). vMA also includes an authentication component allowing direct connection to established target servers without user intervention.