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FlixMLFlixML Studioopen-source generative AI image and video tool

FLUX.2 Klein Image

Text-to-image with FLUX.2 Klein 4B. High-fidelity stills from a prompt, with two optional LoRA slots.

Workflow id: flux2_klein · Text → Image

Calling it

POST /api/image/generate
{
  "workflow": "flux2_klein",
  "prompt": "..."
}

Params

Every input this workflow takes. Your install is the source of truth:GET /api/workflows/flux2_klein returns these as they are on your machine.

  • prompt · str · required
    Natural language sentences, not tags — the opposite of an SDXL prompt. Subject, then action, then style, then context, in that order: word order is weight, so lead with the subject and close with atmosphere. 30-80 words suits most shots. 'A businessman in a charcoal grey suit resting his arms on a bamboo railing at a secluded beach, illustrated in a vintage woodblock print style, calm turquoise water under a hazy afternoon sky.' FLUX.2 has no negative prompt and this graph has no node for one, so describe what you want instead of what you don't — 'sharp focus throughout', not 'not blurry'. For photorealism, name a camera, lens or film stock rather than saying 'professional'.
  • lora_name · str · optional
    Optional LoRA file in the node's loras folder. Leave empty and the slot is removed from the graph entirely. A FLUX.2 LoRA is built for one variant: a Klein 4B LoRA does not load on Klein 9B or on FLUX.2-dev, and a dev LoRA does not load here — the residual stream is 3072 wide on 4B against 6144 on dev, so the tensors do not fit. Match the LoRA's stated base model to the weights in the unet param.
  • lora_strength · float · default 1
    Weight of the first LoRA. Ignored when lora_name is empty.
  • lora_name_2 · str · optional
    Second LoRA, chained after the first — for stacking a concept LoRA on top of a likeness or style one. Same variant rule as lora_name.
  • lora_strength_2 · float · default 1
    Weight of the second LoRA. Ignored when lora_name_2 is empty.
  • width · int · default 832
    Output width
  • height · int · default 832
    Output height
  • seed · int · optional
    Optional. Leave it out and every run is a new random take. Send a seed only to remake an image exactly: the seed a job used is in its record.
  • steps · int · default 4
    Klein is distilled to 4 steps; raise it only when running undistilled FLUX.2 weights through the unet param
  • sampler · str · default euler
  • guidance · float · default 4
    FLUX guidance scale
  • unet · str · default flux-2-klein-4b-fp8.safetensors
  • clip · str · default qwen_3_4b_fp4_flux2.safetensors
  • vae · str · default flux2-vae.safetensors