FLUX 3 Image Klein | Forge Neo Extension

Generate with FLUX 3 Image Klein inside Forge Neo, using the checkpoint, preset and Generate button you already know: text-to-image, editing with up to 10 reference images, and layouts drawn with boxes in the prompt, even on 8 GB GPUs.

Requires an up-to-date Forge Neo (the neo branch). On an older version it stays disabled and says so in the console, and Forge Neo keeps working as usual.

Features 🚀

🖼️ Native Generation

• Runs inside txt2img and img2img: no separate tab, no extra environment

• The distilled model makes an image in 16 steps, about 25 seconds at 1024x1024 on an RTX 2070 with the INT8 file

• The base model runs 50 steps with CFG, made for LoRA training and research

• INT8 files for 8 GB GPUs, the full BF16 files, and NVFP4 for RTX 50 cards

• Uses the same text encoder as Krea 2 and Iris 3B, and the same autoencoder as FLUX.2

🧩 Reference Images

• Edit a picture or combine up to 10 of them, with ImageStitch Integrated and img2img

• An edit with one reference takes about a minute on an RTX 2070

📐 Layout by Boxes

• Add a list of boxes at the end of the prompt, in the format of Black Forest Labs' guide: [top, left, bottom, right] on a 0-1000 grid, with a short description and a name such as <vase_1>

• Works with sd-dynamic-prompts installed

🖱️ Draw the Boxes

• The companion Regional Boxes extension lets you drag on a frame to draw each box, and writes the list into the prompt

• It also places, adds, moves and removes things for box edits

✂️ Edit by Boxes

• With a reference image, add, remove, move or replace things by giving their boxes. The rest of the picture stays as it was

🔌 LoRA

• FLUX 3 LoRAs with the usual <lora:name:weight> syntax, with the BF16 and INT8 files alike

🛡️ Safe by Design

• Changes no Forge Neo file: remove the extension and everything is as it was

• Checks your Forge Neo at startup and tells you which file is missing instead of failing with a generic error

• Other models are not affected

Recommended Settings ⚙️

• Distilled model (_sd_ files): Euler, schedule FLUX.3, 16 steps, CFG 1. The flux3 UI preset sets these

• Base model: Euler, schedule FLUX.3, 50 steps, CFG 3.5

• Leave the negative prompt empty and use sides that are a multiple of 16. For edits with a reference, use Denoising strength 1

Installation 📦

1. Open Forge Neo WebUI and go to Extensions → Install from URL

2. Paste: https://github.com/eduardoabreu81/flux3-image-forge-neo

3. Click Install and restart the WebUI

4. Accept the license on black-forest-labs/flux-3-image-klein-comfy and place the checkpoint, the Qwen3-VL 4B text encoder and flux2-vae in the usual folders (the full file list is in the README)

5. Pick the flux3 UI preset, the checkpoint, and the text encoder and autoencoder under VAE / Text Encoder

Documentation: Wiki · File list · What's new · GitHub

License: the extension is AGPL-3.0. The FLUX 3 Image Klein weights are released under the FLUX Kommunity License and are not included.