FLUX 3 Klein online image generator

What FLUX 3 Klein is

FLUX 3 Klein, also known by its full name FLUX 3 Image Klein, is an image model developed by Black Forest Labs (BFL), the German company that creates the FLUX model family. The Hugging Face repository for the model was created on October 13, 2026 (UTC), and Black Forest Labs’ release notes and press coverage give October 15, 2026 as the release date.

The image model has 5.6 billion parameters and is paired with a separate Qwen3-VL-4B text encoder. According to Black Forest Labs’ documentation and the model card, the model can generate images from text, edit images by instruction, combine up to 10 reference images, control layout with bounding-box coordinates and render text inside images, at up to 4K. This site offers text to image and editing one image, at 1K.

What you can do here

Klein Studio (flux3klein.org) is an unofficial website that lets you run FLUX 3 Klein in your browser through Black Forest Labs’ API. This site is not affiliated with or endorsed by Black Forest Labs.

Here on Klein Studio, you can generate images from text prompts or upload one image and edit it using written instructions. Every visitor gets 3 free images a day at 1K resolution with no sign-up required. For more, there are one-time image packs with no subscription. Failed images are not charged.

Writing prompts that work

The model card states that FLUX 3 Klein is meant to be used with a prompt upsampler (a prompt expander), and that short prompts used directly give mediocre results. It is not confirmed whether Black Forest Labs’ API expands prompts automatically. Because of this, you should write longer, specific prompts rather than two or three words. Describe the subject, the setting, the lighting, and any text you want rendered inside the image.

Here are three example prompt lines you can try:

• A close-up studio photograph of a green ceramic coffee mug on a dark walnut table, soft morning window light from the left, shallow depth of field, the word “MORNING” printed in white sans-serif letters on the mug.
• An architectural drawing of a two-story brick townhouse with black window frames and a small front garden, overcast daylight, drawn in clean black ink lines with muted watercolor wash.
• Edit instruction for an uploaded photo: Replace the background with a quiet snow-covered pine forest at dusk while keeping the subject in the foreground unchanged.

Run it yourself or use the API

The model weights are open but gated on Hugging Face, meaning you must log in and accept the license before you can download the weights. If you want to run the model on your own machine, read our guide to running FLUX 3 Klein in ComfyUI and check the VRAM and hardware requirements, which cover Black Forest Labs’ stated minimum GPU, an NVIDIA RTX 3090 and ComfyUI’s 8 GB INT8 setup; Apple users can also check our note on Mac and Apple Silicon status. Before using the weights or images in a project, review the FLUX Kommunity License v1.0 summary. Developers who prefer cloud generation can read our API guide and pricing breakdown or see how this release relates to the previous generation on our FLUX 3 Klein vs FLUX.2 Klein page. You can also browse example prompts in the gallery, find answers to common questions in the FAQ, or track site and documentation updates in the changelog.