• manages clusters of Xen hosts as single entities
• allows running VMs to be migrated between hosts (including with storage) with minimal downtime
• automatically restarts VMs after host failure ("High Availability")
• facilitates disaster recovery cross-site
• simplifies maintainence through rolling pool upgrade
• collects performance statistics for historical analysis and for alerting
• has a full-featured XML-RPC based API, used by clients such as XenCenter, Xen Orchestra, OpenStack and CloudStack

The xapi toolstack is developed by the xapi project: a sub-project of the Linux Foundation Xen Project.

• Architecture: read about how the components of the xapi toolstack work together
• Features: learn about the features supported by xapi and how they work.
• Designs: explore designs for cross-cutting features.
• Xen API documentation: explore the Xen API
• Futures: find out how the xapi toolstack is likely to change and how you can help.
• Xapi project: learn about the xapi project on the Xen wiki

• Xapi: manages a cluster of Xen hosts, co-ordinating access to network and storage.
• Xenopsd: a low-level "domain manager" which takes care of creating, suspending, resuming, migrating, rebooting domains by interacting with Xen via libxc and libxl.
• Xcp-rrdd: a performance counter monitoring daemon which aggregates "datasources" defined via a plugin API and records history for each.
• Xcp-networkd: a host network manager which takes care of configuring interfaces, bridges and OpenVSwitch instances
• Squeezed: a single host ballooning daemon which "balances" memory between running VMs.
• SM: Storage Manager plugins which connect Xapi's internal storage interfaces to the control APIs of external storage systems.