Download J2

The current release is J2 0.1.0, published July 7, 2026, for macOS on Apple Silicon. Every binary is signed and notarized by Apple.

J2 ships as a single self-contained bundle. It includes the interpreter, the native compiler, and everything the compiler needs, so there is no separate toolchain to install and no network access required to build programs.

Package installer

This is the easiest route. The package is signed, notarized, and stapled, so macOS opens it without warnings. Double-click it and follow the prompts; it installs J2 under /usr/local/j2 and links the j2 command into /usr/local/bin.

Tarball

Prefer an archive you can inspect, or an install that stays inside your home directory? Unpack the tarball and run the bundled installer:

$ tar xzf j2-0.1.0-aarch64-apple-darwin.tar.gz
$ cd j2-0.1.0-aarch64-apple-darwin
$ ./install.sh

The script installs J2 to ~/.j2 and puts the j2 command on your PATH, through /usr/local/bin when it is writable and through your shell profile otherwise. Both locations can be overridden:

$ J2_PREFIX=/opt/j2 J2_BINDIR=/usr/local/bin ./install.sh

The installer finishes by warming the native build cache. That step is safe to interrupt; everyday runs use the interpreter and never need it. A zip archive with identical contents is also available.

First steps

Open a new terminal and check the install:

$ j2 --version
j2 0.1.0

Then run something:

$ echo 'print("hello, world")' > hello.j2
$ j2 hello.j2
hello, world

Native builds with j2 build link with the system linker. If you do not have the Xcode Command Line Tools yet, install them once with xcode-select --install. From here, the Getting Started guide covers the rest.

Editor support

The extension adds syntax highlighting for .j2 files, a run command bound to Cmd+Shift+R, and inline error reporting. Install it from the command line:

$ code --install-extension j2-lang-0.1.0.vsix

Checksums

SHA-256 digests for the 0.1.0 artifacts:

File	SHA-256
j2-0.1.0.pkg	466092a176760c45c85b8f02e4430037d0baf8e5346c22fcfde2a309e1ef406b
j2-0.1.0-aarch64-apple-darwin.tar.gz	6fda8338791730cf7937362acd03e29247719e65785458e62988e1789c842e75
j2-0.1.0-aarch64-apple-darwin.zip	bf4aa57e2e4b53357762df50ca1ad74edd806efd156345132e18193a16149026

Verify a download with shasum -a 256 <file>.

What is in the bundle

The download unpacks to roughly 670 MB on disk. It contains the j2 binary, the native compiler toolchain, the J2 runtime library, and vendored copies of every dependency the compiler may need. This is what makes J2 self-contained: native compilation works on a machine with no development tools and no internet connection.

Platform support

J2 0.1.0 supports macOS on Apple Silicon (aarch64-apple-darwin). It is the only platform the release has been built and tested for. Intel macOS, Linux, and Windows builds are planned; watch the releases page for new artifacts.

Source and license

J2 is open source, dual licensed under the MIT and Apache 2.0 licenses. Release notes and all artifacts live on GitHub Releases. The release bundle also redistributes open source components, listed in the THIRD-PARTY-NOTICES file that ships with it.