The latest Graph API version is:
The Graph API and Marketing API changelogs document versioned and out-of-cycle changes, respective to the API.
Versioned changes are changes introduced with the release of a new API version. Versioned changes typically apply to the newest version immediately and often will apply to other versions at a future date. The changelog accompanying each release indicates which changes apply to the current release and which changes apply to other versions.
Refer to our Upgrade Guide to learn how to upgrade to a new API version.
Out-of-cycle changes are changes introduced outside of our normal, versioned release schedule and typically do not apply to a specific version. Instead, out-of-cycle changes usually apply to all API versions immediately. Because of this, out-of-cycle changes are introduced infrequently.