In addition to the generally available release builds of all currently supported versions of openjdk (Currently 8, 11, 17 and 20) Temurin also publishes "nightly" development builds of all of those streams as well as the upcoming releases (JDK21/22 at the moment) as "nightly" or "early access" builds. You can get these from the nightly downloads page or from the API. Note that while these are not intended for production use they can be used to test a build containing any new fixes which have been put into openjdk along with any new features that will be coming in the next release.

Early access (ea) tagged builds of JDK21+

We have recently changed the way we do the regular nightly builds of JDK21+. Instead of producing regular builds of the latest development code, we are building explicitly from the early access tags when they come out. This is consistent with what OpenJDK does with the builds at https://jdk.java.net/21/ but on a wider range of platforms. Similar to the nightly builds mentioned in the introduction, these are not for production use but may be useful for testing new features as they go into the new codebase. By using the specific early access tags you can also report issues upstream more easily by knowing exactly which tagged level you have discovered any problems with.

You can download the latest ea build from the API by retrieving this (replace linux and x64 with the platform you are interested in:

https://api.adoptium.net/v3/binary/latest/21/ea/linux/x64/jdk/hotspot/normal/adoptium

If you want to download a specific EA build instead of the latest, you can do so using a URL such as:

https://api.adoptium.net/v3/binary/version/jdk-21+32-ea-beta/linux/aarch64/jdk/hotspot/normal/adoptium

The output from java -version for these builds will look like this (but it may change in the future) The -ea indicates that it is build from the early access tag in GitHub:

openjdk version "21-beta" 2023-09-19
OpenJDK Runtime Environment Temurin-21+34-202308031254 (build 21-beta+34-ea)
OpenJDK 64-Bit Server VM Temurin-21+34-202308031254 (build 21-beta+34-ea, mixed mode, sharing)

Using the ea builds with GitHub actions

If you want to pull a Temurin JDK21 ea build in a GitHub action, you can use the following:

     - uses: actions/setup-java@v3
        with:
          java-version: 21-ea
          distribution: temurin

Will you be doing this with earlier releases?

We are looking at whether it makes sense to build ea levels instead of regular nightly head builds of the other supported codebases. If you have a view on whether that would be useful please let us know by commenting in this issue.