Tier 2 Restricted open-weight
What the publisher claims: open weights, open-weights
The one-liner: Two variants with one genuinely permissive license and one non-commercial license.
The six questions
Both the 4B and 9B checkpoints are downloadable from the publisher's Hugging Face repositories.
The 4B model is fully Apache-2.0; the 9B model, the stronger editing model, is under the FLUX Non-Commercial License with an Acceptable Use Policy.
Runs locally on consumer GPUs from roughly 13GB VRAM upward via Diffusers and ComfyUI, with a published reference implementation.
Blog and model-card material covers architecture and benchmarks; the training data and recipe are not published.
Limited: weights and inference code are available, but no training corpus or recipe accompanies them.
Same BFL community channel as FLUX.1; corporate-controlled releases.
License
Apache-2.0 for FLUX.2 [klein] 4B; FLUX Non-Commercial License for FLUX.2 [klein] 9B — license source ↗
- The 9B weights are gated behind acceptance of the FLUX Non-Commercial License and the BFL Acceptable Use Policy
- The smaller 4B variant is genuinely Apache-2.0, so terms differ within the family
What is actually released
- weights (4B, 9B)
- reference implementation and sampling code
- ComfyUI and Diffusers integration
- API endpoint
Why it matters
A direct test of whether a family name means anything: the same 'open weights' label covers Apache-2.0 weights and non-commercial weights in the same release.
Sources
- https://huggingface.co/black-forest-labs/FLUX.2-klein-4B
- https://huggingface.co/black-forest-labs/FLUX.2-klein-9B
- https://bfl.ai/blog/flux2-klein-towards-interactive-visual-intelligence
Derived from the openness dataset behind But Is It Open? — snapshot 2026-11-07 ↗. Scores are qualitative readings of the cited evidence, not verdicts; tier measures openness, not intelligence.