cja

A CMake-compatible build system that generates Ninja build files.

Build a project with a CMakeLists.txt using:

cja
ninja

This is equivalent to the following with CMake:

cmake -Bbuild -GNinja -DCMAKE_BUILD_TYPE=Debug \
  -DCMAKE_COLOR_DIAGNOSTICS=1 -DCMAKE_EXPORT_COMPILE_COMMANDS=1
ninja -Cbuild

Install

pip install cja

Or, if you're in a managed Python environment:

pipx install cja

Comparison to CMake

The build.ninja file is generated in your project root, not in the build directory. To allow multiple build configurations in parallel, the file name is <builddir>.ninja.
Paths are relative to the project root, while CMake uses absolute paths. This is faster, reduces output, and also reduces binary size as paths (e.g. for debug symbols) are shorter. When reading output from a Docker container, this lets you click paths and open the correct files in your local editor.
Instead of a separate tool like CTest, cja generates a phony test target that runs all tests as part of the Ninja build graph, so tests can start as soon as the first test binary is ready.
Colors for compiler diagnostics are enabled by default.
_builddir_/compile_commands.json is always generated.
More colorful, simplified output. For example, when downloading dependencies, cja shows progress bars using Rich, while CMake shows no output (or simple multi-line output when -DFETCHCONTENT_QUIET=0 is specified).

Limitations to keep cja simple:

Only generates Ninja build files.
Out-of-tree builds aren't allowed.
Only supports Linux, macOS, and Windows.
Only supports clang with a GNU-like command line on Windows.

Build Subcommand

cja supports a build subcommand, which runs ninja automatically afterward.

`cja --release` / `cja build --release`

cja --release is equivalent to:

cja -Bbuild-release -DCMAKE_BUILD_TYPE=Release

cja build --release additionally runs ninja:

cja -Bbuild-release -DCMAKE_BUILD_TYPE=Release
ninja -f build-release.ninja

Run Subcommand

cja also generates a run phony target that executes the first executable (or the one set via VS_STARTUP_PROJECT) in your CMakeLists.txt.

Metadata

Release files for cja 0.7.6

For a detailed explanation of source distributions (sdists) and built distributions (wheels), please see the package formats documentation.

Source distribution (sdist)

Source distribution for cja 0.7.6
File	Size	Uploaded
cja-0.7.6.tar.gz	128.3 kB	Oct 5, 2026	Details

Built distribution (wheel)

Table of built distributions (wheels) for cja 0.7.6
File	Interpreter	ABI	Platform	Reset
cja-0.7.6-py3-none-any.whl 137.7 kB Oct 5, 2026	Python 3	none	any	Details

Total release size: 266.0 kB

Release files / cja-0.7.6.tar.gz

Download URL	cja-0.7.6.tar.gz
Size	128.3 kB
Tags	Source
SHA-256 checksum How to use checksums	`5a286df2947b7cc67cd0d7a7a8ddf1957a6d1b09f223d0eefbd4a14974d87efe`
BLAKE2b-256 checksum How to use checksums	`5771c932d8f07dbc61c05318983f80553eb4a5c211e59b257392e3647ecbcbc6`
Upload date	Oct 5, 2026
Uploaded using Trusted Publishing? What is trusted publishing?	Yes
Uploaded via	`twine/7.0.0 CPython/3.13.14`

Provenance

Provenance describes where a file came from. On PyPI, provenance is shared via attestations, which provide a verifiable record of the build or publishing details. View details, limitations and caveats.

Identity

Publishing platform: GitHub Actions
Publishing repository: github.com/jhasse/cja
Publishing commit: github.com/jhasse/cja/tree/d9ddc8703eb4e4c9d7add746636ceabaee689a9d

Workflow

Publishing configuration: github.com/jhasse/cja/blob/d9ddc8703eb4e4c9d7add746636ceabaee689a9d/.github/workflows/release.yml
Publishing logs: github.com/jhasse/cja/actions/runs/37295322160/attempts/1

Artifact

Subject: cja-0.7.6.tar.gz
SHA-256 checksum: 5a286df2947b7cc67cd0d7a7a8ddf1957a6d1b09f223d0eefbd4a14974d87efe Verifying attestations

Release files / cja-0.7.6-py3-none-any.whl

Download URL	cja-0.7.6-py3-none-any.whl
Size	137.7 kB
Tags	Python 3
SHA-256 checksum How to use checksums	`a1564cc169f5411e889731d8b715bb95eb53ff7760aa4d3ee4be552fbebeae9d`
BLAKE2b-256 checksum How to use checksums	`8d00efc4970c6a3fe81be76baed1adf1bd99f3fc868ddc501a4eefdb7204ceb8`
Upload date	Oct 5, 2026
Uploaded using Trusted Publishing? What is trusted publishing?	Yes
Uploaded via	`twine/7.0.0 CPython/3.13.14`

Provenance

Identity

Publishing platform: GitHub Actions
Publishing repository: github.com/jhasse/cja
Publishing commit: github.com/jhasse/cja/tree/d9ddc8703eb4e4c9d7add746636ceabaee689a9d

Workflow

Publishing configuration: github.com/jhasse/cja/blob/d9ddc8703eb4e4c9d7add746636ceabaee689a9d/.github/workflows/release.yml
Publishing logs: github.com/jhasse/cja/actions/runs/37295322160/attempts/1

Artifact

Subject: cja-0.7.6-py3-none-any.whl
SHA-256 checksum: a1564cc169f5411e889731d8b715bb95eb53ff7760aa4d3ee4be552fbebeae9d Verifying attestations