2023 update: a March 2023 commit provides an update on the situation:

The latest released version of Jython remains 2.7.x (see Jython for that).

This doesn't mean that there isn't any progress on a Jython 3. A lot of exploration has taken place away from the official repository, in order not to pollute it with false starts and dead-ends.

Since the beginning of 2021, Jython 3 exploratory work reached a form that merited porting from the experiment to the main of the official repo. Risky design concepts still begin life in the exploratory environment, then arrive as a PR to the official main branch. Please watch the jython-dev mailing list for developements, or the main branch (not master) of the official Jython repo.


Another update: an August 2020 commit clarified that the repository to look at is not the Jython3 one but the main Jython repo. Anyway "The latest version of Jython remains 2.7.x. A Jython 3.x should appear, but exploratory work towards it is not stable at the time of writing. Please watch the jython-dev mailing list for developements."


Update: 9 years after the question has been originally asked the answer now seems to be not in the near future. Most recent commit is now more than two years old (July 18, 2017), and developers say that the 3.x branch is "resting".


My original answer:

5 years after the question has been asked, the answer is still "it will come, but the time frame for an initial release is not clear yet".

What we can say is that now there is a jython3 repository targetting Python 3.5. README.md, dated 28 May 2015, says:

This repo is in the very early stages of development of a release of Jython 3.5. Planned goals are language and runtime compatibility with CPython 3.5, along with continued substantial support of the Python ecosystem.

Jython FAQ page states that:

Jython 3.x development is in progress.

Answer from Diego on Stack Overflow
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Jython
jython.org › jython-3-mvp.html
Jython 3 Features and MVP | Jython
MVP: jython3 command installable on each major OS · MVP: subset of commonly-used python3 command options · Option-compatible with python3 (MVP: a subset) Options specific to Jython (JVM options and others) MVP: speed comparable with CPython (say 2x either way).
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GitHub
github.com › jython › jython3
GitHub - jython/jython3: A sandboxed attempt at v3 (not maintained) · GitHub
This repo represents an attempt made in 2016 to implement a Jython 3.5, that is, with language and runtime compatibility with CPython 3.5, along with continued substantial support of the Python ecosystem. It is a sandbox for that venture. This code having branched from an early 2.7, the architecture is that of Jython 2, without taking advantage of the (then fairly new) dynamic language support.
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When will Jython support Python 3? - Stack Overflow
I m needing Python3 and the objects I m using can t be serialized which means a Python3 implementation of Python without the gil (or making it optional) is needed. 2021-01-05T12:17:54.063Z+00:00 ... Probably the most up to date info on the Jython Website https://www.jython.org/jython-3-roadmap ... More on stackoverflow.com
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Python, Jython, CPython, Libraries, Pip, and Python 2.7 vs 3 - A quick primer
We wrote up a Knowledge Base article a little while back that I wanted to post here. It goes over a variety of questions that are common with regard to Python in Ignition. If you’re looking for information on the topic, take a glance at the linked article. More on forum.inductiveautomation.com
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February 9, 2021
Which Jython version works with Python 3.9
I need to use Python and Jython together. The Python version I need is 3.9. Which Jython release works with that Python 3.9? More on github.com
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February 23, 2024
Python 3.7+ Support
There was an error while loading. Please reload this page · Are there plans to support Python 3.7+ More on github.com
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April 30, 2021
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GitHub
github.com › aaveshdev › jython3
GitHub - aaveshdev/jython3: Jython 3: Python 3 for Java · GitHub
This is the development repository of Jython 3, the implementation of Python 3 in Java.
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Top answer
1 of 4
58

2023 update: a March 2023 commit provides an update on the situation:

The latest released version of Jython remains 2.7.x (see Jython for that).

This doesn't mean that there isn't any progress on a Jython 3. A lot of exploration has taken place away from the official repository, in order not to pollute it with false starts and dead-ends.

Since the beginning of 2021, Jython 3 exploratory work reached a form that merited porting from the experiment to the main of the official repo. Risky design concepts still begin life in the exploratory environment, then arrive as a PR to the official main branch. Please watch the jython-dev mailing list for developements, or the main branch (not master) of the official Jython repo.


Another update: an August 2020 commit clarified that the repository to look at is not the Jython3 one but the main Jython repo. Anyway "The latest version of Jython remains 2.7.x. A Jython 3.x should appear, but exploratory work towards it is not stable at the time of writing. Please watch the jython-dev mailing list for developements."


Update: 9 years after the question has been originally asked the answer now seems to be not in the near future. Most recent commit is now more than two years old (July 18, 2017), and developers say that the 3.x branch is "resting".


My original answer:

5 years after the question has been asked, the answer is still "it will come, but the time frame for an initial release is not clear yet".

What we can say is that now there is a jython3 repository targetting Python 3.5. README.md, dated 28 May 2015, says:

This repo is in the very early stages of development of a release of Jython 3.5. Planned goals are language and runtime compatibility with CPython 3.5, along with continued substantial support of the Python ecosystem.

Jython FAQ page states that:

Jython 3.x development is in progress.

2 of 4
38

Jython roadmap is definitely outdated.
However, on Frank Wierzbicki's Weblog (one of Jython's main developers) you can get an update, telling that Python 3 is definitely on the radar.

Unfortunately, it is not yet clear when, as it is stated in a comment in that same blog from 2010:

Jython will reach 2.6 and later a 3.x, but it's hard to give a solid time frame. I'm hoping to get a 2.6 out in a few months.

In an interview in 2017, Wierzbicki stated that Python 3 is desirable but difficult.

Langfristig wollen wir eine 3.x-Version veröffentlichen, aber das ist ein langwieriger Prozess, weil es eine große Menge an Veränderungen in der 3.x-Serie gab.

English:

We want to publish a version 3.x in the long run, but that is a drawn-out process, because there were a lot of changes in the 3.x series.

Jython – Python in der Java-Welt [Pirates of the JVM], JAXenter, 2017-04-12.

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Jython
jython.org › jython-3-roadmap.html
Jython 3 Roadmap | Jython
Outline architecture for modules and importers, giving special attention to the semantics of Java packages and modules. Advances in the module concept in Python should allow us to avoid some of the special cases and thrashing around we find in Jython 2.
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GitHub
github.com › AkramLZ › jython3
GitHub - AkramLZ/jython3: An updated version of Jython, supporting Python 3
This is the development repository of Jython, the implementation of Python in Java.
Author   AkramLZ
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Readthedocs
python-3-patterns-idioms-test.readthedocs.io › en › latest › Jython.html
Jython — Python 3 Patterns, Recipes and Idioms
Python is designed with classes from the ground up and provides pure support for object-oriented programming (both C++ and Java violate purity in various ways). Python scales up so that you can create large programs without losing control of the code. Java projects have been quickly created using Jython, then later optimized by rewriting into Java sections of the Jython code that have profiled as bottlenecks.
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Jython
jython.org
Home | Jython
The Jython project provides implementations of Python in Java, providing to Python the benefits of running on the JVM and access to classes written in Java. The current release (a Jython 2.7.x) only supports Python 2 (sorry). There is work towards a Python 3 in the project’s GitHub repository ...
Find elsewhere
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Pybenchmarks
pybenchmarks.org › u64q › jython.php
Jython vs Python 3 | Python Interpreters Benchmarks
Each chart bar shows, for one unidentified benchmark, how much the fastest Jython program used compared to the fastest Python 3 program.
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Inductive Automation
forum.inductiveautomation.com › ignition
Python, Jython, CPython, Libraries, Pip, and Python 2.7 vs 3 - A quick primer - Ignition - Inductive Automation Forum
February 9, 2021 - We wrote up a Knowledge Base article a little while back that I wanted to post here. It goes over a variety of questions that are common with regard to Python in Ignition. If you’re looking for information on the topic…
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GitHub
github.com › jython › jython › issues › 312
Which Jython version works with Python 3.9 · Issue #312 · jython/jython
February 23, 2024 - I need to use Python and Jython together. The Python version I need is 3.9. Which Jython release works with that Python 3.9?
Author   jython
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GitHub
github.com › jython › jython › issues › 95
Python 3.7+ Support · Issue #95 · jython/jython
April 30, 2021 - Hi, Are there plans to support Python 3.7+?
Author   jython
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Coderanch
coderanch.com › t › 687057 › languages › Confused-Jython-Python
Confused about Jython/Python (Jython/Python forum at Coderanch)
Is Jython the same language as Python? Yes. Jython is an implementation of the Python language for the Java platform. Jython 2.7 implements the same language as CPython 2.7, and nearly all of the Core Python standard library modules. (CPython is the C implementation of the Python language.)
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Wikipedia
en.wikipedia.org › wiki › Jython
Jython - Wikipedia
June 10, 2026 - Jython programs can import and use any Java class. Except for some standard modules, Jython programs use Java classes instead of Python modules. Jython includes almost all of the modules in a standard Python language distribution, lacking only some of the modules implemented originally in C.
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Image.sc
forum.image.sc › development
Will Jython 3 ever happen - Development - Image.sc Forum
March 26, 2024 - The other day I was reading the post Python syntax highlighting stopped working in Fiji script editor - Usage & Issues - Image.sc Forum and there I noticed that @karlduderstadt and @albertcardona mentioned the following: Even if I merged them, I would not be able to release a new version of ...
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Processing
py.processing.org › tutorials › python-jython-java
Python, Jython and Java \ Tutorials
Python Mode for Processing extends the Processing Development Environment with the Python programming language.
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JMRI
jmri.org › help › en › html › tools › scripting › Python3.shtml
JMRI: Python 3 Introduction
Scripts should start with import jmri as jmri import java exec( open("jython/jmri_bindings.py3").read() ) The third line is the Py3 syntax to read and execute another script file.
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GraalVM
graalvm.org › jdk22 › reference-manual › python › Modern-Python-on-JVM
Modern Python on the JVM
For Python version 2 (now EOL), Jython is the de facto means of interfacing Python and Java. Most existing Jython code that uses Java integration will be based on a stable Jython release—however, these are only available in Python 2.x versions.
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GitHub
github.com › jython › jython › issues › 24
Future of Jython · Issue #24 · jython/jython
Just curious as to the roadmap for this implementation of Python given that Python 2 is at the end of its life very soon. Will there be an implementation for Python 3 worked on? Python 3.8 provides many improvements and new features over...
Author   jython