A full build of each release which can be used in a script tag is available from cdnjs or from the OpenLayers site. You will need both the JS build and the CSS files; see the examples or the Quickstart tutorial for usage.

Archive	Description
v4.2.0-dist.zip	Includes a full build of the library, a debug build, and library CSS.
v4.2.0.zip	Includes all of the above plus examples, API docs, and sources.

See the v4.2.0 release page for a changelog and any special upgrade notes.

For archives of previous releases, see the complete list of releases.

To get the source, for example, to create a custom build, you can install the OpenLayers NPM package, or clone the Github repo.