FLUX.2 Klein 4B or 9B: Licence and Model-Card Guide

By Dominic Marrocco, 42 UK Research. Technical claims below are bounded to the linked primary sources.

Canadian licence-and-selection edition · evidence review: 5 August 2026

The two cited releases do not have the same licence

“FLUX.2 klein” is not enough information for a deployment decision. The official 4B base card publishes that model under Apache 2.0. The official 9B card identifies its release under the FLUX non-commercial licence. Read the current linked terms for the exact model revision; this technical guide is not legal advice.

Facts to capture before choosing weights

• Exact repository: distinguish FLUX.2-klein-base-4B from FLUX.2-klein-9B.
• Release type: the cited 4B is a base model; the cited 9B is described as a four-step distilled release.
• Licence: record the licence attached to the exact weights, not the family name.
• Hardware evidence: preserve the publisher’s conditions. “As little as 13 GB” on the 4B card is not a universal minimum for every workflow.
• 9B hardware evidence: its model card says the model fits in about 29 GB of VRAM; that number must stay attached to the cited 9B release and setup.
• Intended output: both cited cards describe image generation and editing, but a production workflow still needs its own acceptance tests.

ComfyUI deployment record

Install ComfyUI only through a maintained path linked from its official repository. Check the current official requirements for platform and dependency compatibility. Store the model revision, workflow JSON, dependency versions and launch flags with the result. If an out-of-memory condition occurs, apply the official troubleshooting guidance and record each change.

Evidence routes on 42 UK

The installation matrix tracks setup paths without freezing obsolete dependency advice. The validated workflow library separates tested assets from drafts. The low-VRAM benchmark hub defines what must be measured before a memory claim can be certified.