Since GitLab 9.0, API V4 is the preferred version to be used.
V3 will remain working until at least GitLab 9.3. The V3 API documentation is still [available](https://gitlab.com/gitlab-org/gitlab-ce/blob/8-16-stable/doc/api/README.md).
API V3 will be removed in GitLab 9.5, to be released on August 22, 2017. In the
meantime, we advise you to make any necessary changes to applications that use
V3. The V3 API documentation is still [available](https://gitlab.com/gitlab-org/gitlab-ce/blob/8-16-stable/doc/api/README.md).