[Black Forest Labs](/ai-gateway/models/labs/bfl) # FLUX.2 \[klein\] 4B FLUX.2 \[klein\] 4B is Black Forest Labs's Apache 2.0 licensed compact image model. It delivers sub-second text-to-image, image editing, and multi-reference generation from a single checkpoint. Your use is subject to Black Forest Labs's [Terms](https://bfl.ai/legal/terms-of-service) & [Privacy](https://bfl.ai/legal/privacy-policy) Policies. Image Gen [Use with AI Gateway](https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Futm_source%3Dgateway-model-page%26utm_campaign%3Dai-gateway-models&title=Get+Started+with+Vercel+AI+Gateway) [View docs](https://vercel.com/docs/ai-gateway) AI SDKChat Completions ``` 1import { experimental_generateImage as generateImage } from 'ai'; 2 3const result = await generateImage({ 4 model: 'bfl/flux-2-klein-4b', 5 prompt: 'A red balloon on a wooden table.' 6}); ``` [Read docs](https://vercel.com/docs/ai-gateway/sdks-and-apis/ai-sdk) [Overview](/ai-gateway/models/flux-2-klein-4b) [About](/ai-gateway/models/flux-2-klein-4b/about) [Providers](/ai-gateway/models/flux-2-klein-4b/providers) [Similar](/ai-gateway/models/flux-2-klein-4b/similar) [FAQ](/ai-gateway/models/flux-2-klein-4b/faq) ## [Copy link to heading](#playground)Playground Try out FLUX.2 \[klein\] 4B by Black Forest Labs. Usage is billed to your team at API rates. Free users (those who haven't made a payment) get $5 of credits every 30 days. ![bfl logo](/vc-ap-vercel-marketing/_next/image?url=https%3A%2F%2F7nyt0uhk7sse4zvn.public.blob.vercel-storage.com%2Fdocs-assets%2Fstatic%2Fdocs%2Fai-gateway%2Flogos%2Fblackforestlabs.png&w=48&q=75)FLUX.2 \[klein\] 4B Prompt Describe what you want the model to generate. Reference images(optional) Add up to 4 images Images to generate 1234 ![bfl logo](/vc-ap-vercel-marketing/_next/image?url=https%3A%2F%2F7nyt0uhk7sse4zvn.public.blob.vercel-storage.com%2Fdocs-assets%2Fstatic%2Fdocs%2Fai-gateway%2Flogos%2Fblackforestlabs.png&w=96&q=75) Your generated image will appear here ## [Copy link to heading](#providers)Providers Route requests across multiple providers. Copy a provider slug to set your preference. Visit the [docs](/docs/ai-gateway/provider-options) for more info. Using a provider means you agree to their terms, listed under Legal. | Provider | | --- | | Input | Output | Cache | Web Search | Capabilities | ZDR | No Training | Free Tier | Release Date | | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | ![bfl logo](/vc-ap-vercel-marketing/_next/image?url=https%3A%2F%2F7nyt0uhk7sse4zvn.public.blob.vercel-storage.com%2Fdocs-assets%2Fstatic%2Fdocs%2Fai-gateway%2Flogos%2Fblackforestlabs.png&w=48&q=75) [Black Forest Labs](/ai-gateway/models/providers/bfl) Legal:[Terms](https://bfl.ai/legal/terms-of-service)•[Privacy](https://bfl.ai/legal/privacy-policy) | | $0.014/MP | | — | | | | | 01/15/2026 | | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ## [Copy link to heading](#more-models-by-black-forest-labs)More models by Black Forest Labs All Image Video | Model | | --- | | Context | Latency | Throughput | Input | Output | Cache | Web Search | Capabilities | Providers | ZDR | No Training | Free Tier | Release Date | | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | ![bfl logo](/vc-ap-vercel-marketing/_next/image?url=https%3A%2F%2F7nyt0uhk7sse4zvn.public.blob.vercel-storage.com%2Fdocs-assets%2Fstatic%2Fdocs%2Fai-gateway%2Flogos%2Fblackforestlabs.png&w=48&q=75) [bfl/flux\-3-video](/ai-gateway/models/flux-3-video) | | | | | $0.06/sec+2 more | | — | | ![bfl logo](/vc-ap-vercel-marketing/_next/image?url=https%3A%2F%2F7nyt0uhk7sse4zvn.public.blob.vercel-storage.com%2Fdocs-assets%2Fstatic%2Fdocs%2Fai-gateway%2Flogos%2Fblackforestlabs.png&w=48&q=75) | | | | 08/04/2026 | | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | ![bfl logo](/vc-ap-vercel-marketing/_next/image?url=https%3A%2F%2F7nyt0uhk7sse4zvn.public.blob.vercel-storage.com%2Fdocs-assets%2Fstatic%2Fdocs%2Fai-gateway%2Flogos%2Fblackforestlabs.png&w=48&q=75) [bfl/flux-2-klein-9b](/ai-gateway/models/flux-2-klein-9b) | | | | | $0.015/MP | | — | | ![bfl logo](/vc-ap-vercel-marketing/_next/image?url=https%3A%2F%2F7nyt0uhk7sse4zvn.public.blob.vercel-storage.com%2Fdocs-assets%2Fstatic%2Fdocs%2Fai-gateway%2Flogos%2Fblackforestlabs.png&w=48&q=75) | | | | 01/15/2026 | | | ![bfl logo](/vc-ap-vercel-marketing/_next/image?url=https%3A%2F%2F7nyt0uhk7sse4zvn.public.blob.vercel-storage.com%2Fdocs-assets%2Fstatic%2Fdocs%2Fai-gateway%2Flogos%2Fblackforestlabs.png&w=48&q=75) [bfl/flux-2-flex](/ai-gateway/models/flux-2-flex) | | | | | $0.06/MP | | — | | ![bfl logo](/vc-ap-vercel-marketing/_next/image?url=https%3A%2F%2F7nyt0uhk7sse4zvn.public.blob.vercel-storage.com%2Fdocs-assets%2Fstatic%2Fdocs%2Fai-gateway%2Flogos%2Fblackforestlabs.png&w=48&q=75) | | | | 11/25/2025 | | | ![bfl logo](/vc-ap-vercel-marketing/_next/image?url=https%3A%2F%2F7nyt0uhk7sse4zvn.public.blob.vercel-storage.com%2Fdocs-assets%2Fstatic%2Fdocs%2Fai-gateway%2Flogos%2Fblackforestlabs.png&w=48&q=75) [bfl/flux-kontext-max](/ai-gateway/models/flux-kontext-max) | 512 | | | | $0.08/img | | — | | ![bfl logo](/vc-ap-vercel-marketing/_next/image?url=https%3A%2F%2F7nyt0uhk7sse4zvn.public.blob.vercel-storage.com%2Fdocs-assets%2Fstatic%2Fdocs%2Fai-gateway%2Flogos%2Fblackforestlabs.png&w=48&q=75) | | | | 05/29/2025 | | | ![bfl logo](/vc-ap-vercel-marketing/_next/image?url=https%3A%2F%2F7nyt0uhk7sse4zvn.public.blob.vercel-storage.com%2Fdocs-assets%2Fstatic%2Fdocs%2Fai-gateway%2Flogos%2Fblackforestlabs.png&w=48&q=75) [bfl/flux-kontext-pro](/ai-gateway/models/flux-kontext-pro) | 512 | | | | $0.04/img | | — | | ![bfl logo](/vc-ap-vercel-marketing/_next/image?url=https%3A%2F%2F7nyt0uhk7sse4zvn.public.blob.vercel-storage.com%2Fdocs-assets%2Fstatic%2Fdocs%2Fai-gateway%2Flogos%2Fblackforestlabs.png&w=48&q=75) ![prodia logo](/vc-ap-vercel-marketing/_next/image?url=https%3A%2F%2F7nyt0uhk7sse4zvn.public.blob.vercel-storage.com%2Fdocs-assets%2Fstatic%2Fdocs%2Fai-gateway%2Flogos%2Fprodia.png&w=48&q=75) | | | | 05/29/2025 | | | ![bfl logo](/vc-ap-vercel-marketing/_next/image?url=https%3A%2F%2F7nyt0uhk7sse4zvn.public.blob.vercel-storage.com%2Fdocs-assets%2Fstatic%2Fdocs%2Fai-gateway%2Flogos%2Fblackforestlabs.png&w=48&q=75) [bfl/flux-pro-1.0-fill](/ai-gateway/models/flux-pro-1.0-fill) | | | | | $0.05/img | | — | | ![bfl logo](/vc-ap-vercel-marketing/_next/image?url=https%3A%2F%2F7nyt0uhk7sse4zvn.public.blob.vercel-storage.com%2Fdocs-assets%2Fstatic%2Fdocs%2Fai-gateway%2Flogos%2Fblackforestlabs.png&w=48&q=75) | | | | 10/01/2024 | | ## [Copy link to heading](#about-flux2-klein-4b)About FLUX.2 \[klein\] 4B Black Forest Labs released FLUX.2 \[klein\] 4B on January 15, 2026 as the entry point of the Klein family: compact image models Black Forest Labs positions for minimal latency. "Klein" is German for "small," reflecting the model's compact parameter footprint and minimal latency target. The Apache 2.0 license separates Klein 4B from the rest of the FLUX family. Klein 9B carries the FLUX Non-Commercial License (NCL), and FLUX.2 Pro is a proprietary API model. Klein 4B places no commercial use restrictions on its weights. You can deploy it in commercial products, include it in open-source projects, and redistribute derivative works without seeking additional permission from Black Forest Labs. The model unifies text-to-image generation, image-to-image editing, and multi-reference generation in a single checkpoint. Black Forest Labs describes Klein 4B as "compact but capable." The entire inference pipeline targets under 500 milliseconds. ## [Copy link to heading](#what-to-consider-when-choosing-a-provider)What To Consider When Choosing a Provider - Configuration: Apache 2.0 licensing means you can incorporate Klein 4B weights into commercial products, fork them, modify them, and redistribute them. That's a meaningful distinction for teams with open-source or compliance requirements. Check N/A for the managed API. - Zero Data Retention: Zero Data Retention is offered on a per-provider and model basis. See the [documentation](https://vercel.com/docs/ai-gateway/security-and-compliance/zdr) for details. - Authentication: AI Gateway authenticates requests using an [API key](https://vercel.com/docs/ai-gateway/authentication-and-byok#api-key-authentication) or [OIDC token](https://vercel.com/docs/ai-gateway/authentication-and-byok#oidc-token-authentication). You do not need to manage provider credentials directly. ## [Copy link to heading](#when-to-use-flux2-klein-4b)When to Use FLUX.2 \[klein\] 4B ### Best for - Apache 2.0 licensing requirements: Klein 4B is the only FLUX.2 model with unrestricted commercial use rights for commercial products and open-source projects - Sub-second latency: Interactive design tools, live creative interfaces, and agentic visual loops where speed is a product requirement - One-model workflows: Text-to-image, image editing, and multi-reference generation unified in a single checkpoint ### Consider alternatives when - Maximum output quality: FLUX.2 Klein 9B or FLUX.2 Pro deliver higher fidelity - Masked region inpainting: FLUX.1 Fill Pro is purpose-built for mask-based fill rather than generative or editing tasks ## [Copy link to heading](#conclusion)Conclusion FLUX.2 \[klein\] 4B is the Apache 2.0 entry in the FLUX.2 lineup, capable of sub-second image generation and editing. If open licensing and a compact, fast model are the requirements, Klein 4B is the right starting point in the FLUX.2 family.