Java 21 licensing and the LTS update rules.

Java 21 is the current Long-Term Support (LTS) release, and the most common question about it is deceptively simple: is it free? The accurate answer is “yes, for now, under specific rules” — and the “for now” is the part that matters. Oracle JDK 21 is distributed under the No-Fee Terms and Conditions (NFTC) licence, which permits free production use but attaches a time limit to the free updates. This article explains the LTS update rules for Java 21: what is free, when that changes, and how to avoid the cliff edge.

Java 21 is an LTS release — why that matters

Java follows a six-month release cadence, but only certain versions are designated Long-Term Support. Java 21, released in September 2023, is one of them — the LTS line that followed Java 17. Enterprises overwhelmingly standardise on LTS versions because they receive a long, predictable stream of updates rather than being superseded within months.

The LTS designation is a release-engineering decision, not a licensing one — but the two interact, because Oracle’s NFTC free period is defined in terms of the LTS cadence. Understanding Java 21’s licensing means understanding how the NFTC clock is tied to the arrival of the next LTS release.

Java 21 ships under the NFTC licence

Oracle JDK 21 is distributed under the No-Fee Terms and Conditions licence — the same licence introduced with Oracle JDK 17. The NFTC is a genuine improvement on the OTN licence that governed Oracle JDK 11 to 16: where OTN forbade production use without a subscription, the NFTC permits free use of Oracle JDK 21 including production, commercial and internal business use.

So, as things stand, an enterprise can legitimately download Oracle JDK 21 and run customer-facing and internal production workloads on it at no charge. That is a real and useful freedom. But it is a freedom with an expiry condition built into the licence, and reading only the first half of the NFTC — “free for production” — is how enterprises walk into the second half unprepared.

The catch: the NFTC free period has a clock

The NFTC permits free use of a release only for a defined period. For an LTS release such as Java 21, Oracle’s stated rule is that free NFTC use runs until one full year after the next LTS release is delivered. The next LTS after Java 21 is Java 25, expected in September 2025. One year on from that — in or around September 2026 — the NFTC free period for Oracle JDK 21 is set to end.

What ends is not your ability to keep running Java 21. It is Oracle’s provision of free updates to Oracle JDK 21 under the NFTC. After that date, Oracle JDK 21 updates — including security patches — move to paid-subscription terms. The licence does not reach back and make your existing deployment illegal; it stops the free flow of patches going forward.

What happens when the free period ends

The end of the NFTC free period creates a decision point that is sometimes called the update cliff. After it, an enterprise still running Oracle JDK 21 has three honest options.

Buy an Oracle Java SE subscription to continue receiving Oracle’s updates for Oracle JDK 21 — priced, like all current Oracle Java subscriptions, on the employee metric.

Stop updating and continue running the last free build of Oracle JDK 21 — which is licence-compliant but means running software that no longer receives security patches, an outcome no serious security posture should accept.

Move to a free OpenJDK 21 distribution — Eclipse Temurin, Amazon Corretto, Azul Zulu and others publish OpenJDK 21 builds that continue to receive updates at no charge, with no subscription and no cliff.

The cliff is only dangerous to enterprises that did not see it coming. Planned for in advance, it is simply a scheduled decision.

Oracle JDK 21 versus OpenJDK 21

It is essential to separate “Java 21” the platform from “Oracle JDK 21” the specific Oracle build. Java 21 the platform is implemented by OpenJDK, and multiple vendors publish OpenJDK 21 builds. Only Oracle’s own build is governed by the NFTC and its clock.

The free OpenJDK 21 distributions are licensed under the GPL v2 with the Classpath Exception — an open-source licence that permits free production use indefinitely, with no time limit and no subscription. Their updates are free for the supported life of the release. So the NFTC clock is, in effect, a property of Oracle’s build specifically — not of Java 21 itself. An enterprise that wants Java 21 without any licensing clock simply chooses an OpenJDK 21 distribution instead of Oracle’s.

The practical Java 21 update rules

Pulled together, the rules for running Java 21 sensibly are straightforward. Know which build you are running — Oracle JDK 21 or an OpenJDK 21 distribution — because they carry different licences. If you run Oracle JDK 21, record the NFTC free-period end date (around September 2026) as a hard milestone, not a vague future event. Decide before that date whether you will subscribe or move to OpenJDK, and execute the decision with time to spare.

Above all, never let the choice be made by default. The worst Java 21 outcome is an enterprise that drifts past the NFTC cliff still on Oracle JDK 21, then either absorbs a surprise subscription cost or, worse, quietly stops patching a production runtime. Both are entirely avoidable with a date in a calendar and a decision made in advance.

Frequently asked questions

Is Java 21 free to use in production?

Oracle JDK 21 is free for production use under the NFTC licence for now. Free OpenJDK 21 distributions are free for production use indefinitely under the open-source GPL v2 with Classpath Exception.

When does Java 21 stop being free under the NFTC?

Oracle's NFTC free period for an LTS release runs until one year after the next LTS release. With Java 25 expected in September 2025, the NFTC free period for Oracle JDK 21 is set to end around September 2026.

What happens after the NFTC free period for Java 21 ends?

You can keep running Java 21, but Oracle JDK 21 updates move to paid-subscription terms. The options are to buy an Oracle Java SE subscription, stop updating, or move to a free OpenJDK 21 distribution.

Is Oracle JDK 21 the same as OpenJDK 21?

They build Java 21 from the same source, but Oracle JDK 21 is governed by the NFTC with its time limit, while OpenJDK 21 distributions are under the open-source GPL v2 with Classpath Exception and are free indefinitely.

How do we avoid the Java 21 update cliff?

Record the NFTC free-period end date as a hard milestone, and decide in advance whether to subscribe or move to a free OpenJDK 21 distribution. The cliff is only a risk to enterprises that do not plan for it.

Conclusion

Java 21 licensing is a story of a freedom with a deadline. Oracle JDK 21 under the NFTC is genuinely free to run in production today, which is a real improvement on the OTN era — but the licence has a clock, and that clock is set to run out around September 2026. The enterprises that handle Java 21 well are not the ones that read “free for production” and stopped; they are the ones that read the whole licence, put the cliff date on a roadmap, and decided in advance whether to subscribe or move to a free OpenJDK 21 build that has no clock at all. Treat the NFTC free period as a scheduled milestone, not a surprise, and Java 21 stays exactly as free as you planned for it to be.