License
| Component | License | Covers |
|---|---|---|
Brain / umbrella (z4j, and the z4j-brain compatibility shim that installs it) |
AGPL-3.0-or-later | Dashboard, REST API, WebSocket server, Postgres models. pip install z4j installs this, so anything it is combined with carries the same obligations |
| Agent packages | Apache 2.0 | z4j-core, z4j-bare, z4j-django, z4j-flask, z4j-fastapi, z4j-celery, z4j-rq, z4j-dramatiq, z4j-huey, z4j-arq, z4j-taskiq, and all six scheduler adapters |
Companion scheduler (z4j-scheduler) |
Apache 2.0 | The engine-agnostic dynamic scheduler process that runs beside the brain |
Three install paths, three licence outcomes
Section titled “Three install paths, three licence outcomes”| Command | What you install | Licence you end up with |
|---|---|---|
pip install z4j or pip install "z4j[...]" |
Brain + core + optional adapters | AGPL-3.0-or-later |
pip install z4j-<framework> z4j-<engine> |
Agents only | Apache 2.0 |
docker run z4jdev/z4j |
Brain in a container; your app venv untouched | Brain AGPL-3.0 (isolated); app agents Apache 2.0 |
The z4j package is AGPL because it ships the brain itself (the z4j_brain code is inside the z4j wheel; z4j-brain is a metadata-only shim that depends on z4j), not because its own __init__.py contains anything substantive. If AGPL is incompatible with your environment, install the individual agent packages directly - they are all Apache 2.0 and carry no copyleft obligation.
What this means for you
Section titled “What this means for you”Self-hosting the brain
Section titled “Self-hosting the brain”Free. Forever. You can run z4j for your own organization without any obligation beyond AGPL compliance (which, for internal use, means nothing extra - AGPL triggers on network distribution, not internal deployment).
Building on agents
Section titled “Building on agents”Apache 2.0. Your application code is not AGPL-tainted. You can use z4j agents in proprietary software with no license concern - as long as you install the agent packages directly (not via the z4j package, which ships the AGPL brain).
SaaS-ifying the brain
Section titled “SaaS-ifying the brain”If you take z4j and serve it to other companies over a network (i.e., you build a hosted z4j as a SaaS), AGPL requires you to publish your modifications. This is by design - we want a level playing field.
Commercial license
Section titled “Commercial license”If your organization can't use AGPL (legal policy, compliance, whatever), contact licensing@z4j.com for a commercial license. No gotchas.
Commitments
Section titled “Commitments”- Every released version keeps its license permanently. We never retroactively re-license.
- Security fixes always ship in the open-source release on the same day as any commercial release.
- Commercial direction is announced openly when (and if) it lands.
Why AGPL + Apache (not MIT everywhere)
Section titled “Why AGPL + Apache (not MIT everywhere)”MIT-everywhere enables SaaS competitors to wrap your project without contributing back. We want:
- Agents in your app -> no friction -> Apache 2.0.
- Brain as infrastructure -> contribute back if you SaaS-ify -> AGPL.
This is the same pattern PostHog, Plausible, Minio, and others use.
No "free forever" pledge
Section titled “No "free forever" pledge”We make no "free forever" pledge because we've seen other projects make that claim then walk it back. What we commit to:
- License stability on shipped releases.
- Honest communication.
- Security parity between open-source and any future commercial offering.
Contributor license
Section titled “Contributor license”Contributors sign off with DCO (Developer Certificate of Origin). No CLA. See CONTRIBUTING.md in the repo.