Black Forest Labs vs StepFun: Token Pricing, Speed & Intelligence
Full comparison of Black Forest Labs and StepFun — live token pricing, latency, throughput, context window, strengths, weaknesses, and best use cases. Rates sourced from public APIs — verify before use.
Black Forest Labs
FLUX 1.1 Pro Ultra — the quality benchmark for commercial image generation
Black Forest Labs created FLUX, the model family that has become the quality benchmark for both open and commercial image generation. FLUX 1.1 Pro Ultra produces photorealistic images at up to 4MP resolution. The 2026 lineup adds FLUX 1.1 Pro Ultra (highest quality), FLUX 1.1 Pro (production), FLUX.1 Dev (open-weight, fine-tuning), and FLUX.1 Schnell (open-weight, fastest). FLUX models are available via the BFL API and through Replicate, fal.ai, and other inference platforms.
StepFun
Step-5 — Chinese frontier LLM with strong multimodal and reasoning capability
StepFun is a Chinese AI startup developing the Step model series. Step-5 Preview is the frontier tier, competing with top Chinese and international models on reasoning and multimodal benchmarks. Step-3.7 Flash is the efficient tier for cost-sensitive workloads. StepFun is backed by Tencent and focuses on enterprise and developer API access.
Key metric comparison
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Live token pricing
Strengths and weaknesses
Black Forest Labs
StepFun
Key differentiators
FLUX 1.1 Pro Ultra produces the highest-quality AI images available — consistently outperforming Stable Diffusion and competing with Midjourney on photorealism — with open-weight Dev/Schnell variants for self-hosting.
Step-5 is StepFun's frontier reasoning model with multimodal capability, backed by Tencent — positioned as a competitive alternative to Qwen and ERNIE for Chinese enterprise workloads.
Frequently asked questions
Black Forest Labs FAQs
What is the difference between FLUX 1.1 Pro Ultra and FLUX.1 Dev?
FLUX 1.1 Pro Ultra is a commercial API model offering the highest quality output at up to 4MP resolution. FLUX.1 Dev is an open-weight model available for self-hosting and fine-tuning, with slightly lower quality than Pro Ultra but full weight access.
How does FLUX compare to Stable Diffusion 3.5?
FLUX consistently outperforms SD 3.5 on image quality benchmarks, particularly for photorealism and prompt adherence. FLUX Schnell is also significantly faster than SD 3.5 for equivalent quality.
Where can I access FLUX models?
FLUX models are available via the BFL API directly, and through Replicate, fal.ai, Novita AI, and other inference platforms. FLUX.1 Dev and Schnell weights are also available on Hugging Face for self-hosting.
StepFun FAQs
What is StepFun?
StepFun is a Chinese AI startup backed by Tencent, developing the Step model series. Step-5 Preview is the frontier tier and Step-3.7 Flash is the efficient tier, both available via the StepFun API.
How much does the StepFun API cost?
Step-5 Preview is $1.00/$2.70 per 1M input/output tokens. Step-3.7 Flash is $0.20/$1.15 per 1M tokens. See platform.stepfun.com/docs/pricing for current rates.
Does Step-5 support multimodal input?
Yes. Step-5 Preview supports text, image, and video understanding in a single API call, making it suitable for multimodal enterprise applications.
Provider resources
Black Forest Labs — FLUX 1.1 Pro Ultra — the quality benchmark for commercial image generation
Black Forest Labs created FLUX, the model family that has become the quality benchmark for both open and commercial image generation. FLUX 1.1 Pro Ultra produces photorealistic images at up to 4MP resolution. The 2026 lineup adds FLUX 1.1 Pro Ultra (highest quality), FLUX 1.1 Pro (production), FLUX.1 Dev (open-weight, fine-tuning), and FLUX.1 Schnell (open-weight, fastest). FLUX models are available via the BFL API and through Replicate, fal.ai, and other inference platforms.
FLUX 1.1 Pro Ultra produces the highest-quality AI images available — consistently outperforming Stable Diffusion and competing with Midjourney on photorealism — with open-weight Dev/Schnell variants for self-hosting.
StepFun — Step-5 — Chinese frontier LLM with strong multimodal and reasoning capability
StepFun is a Chinese AI startup developing the Step model series. Step-5 Preview is the frontier tier, competing with top Chinese and international models on reasoning and multimodal benchmarks. Step-3.7 Flash is the efficient tier for cost-sensitive workloads. StepFun is backed by Tencent and focuses on enterprise and developer API access.
Step-5 is StepFun's frontier reasoning model with multimodal capability, backed by Tencent — positioned as a competitive alternative to Qwen and ERNIE for Chinese enterprise workloads.
Key strengths compared
Black Forest Labs
- FLUX 1.1 Pro Ultra: highest-quality commercial image generation available
- FLUX.1 Dev and Schnell: open-weight models for fine-tuning and self-hosting
- FLUX.1 Schnell: fastest open-weight image generation model
- Newer company with smaller ecosystem than Stable Diffusion
- Pro models require API access — no self-hosting for highest quality
StepFun
- Step-5 Preview is competitive with top Chinese frontier models on reasoning benchmarks
- Step-3.7 Flash at $0.20/$1.15 per 1M tokens offers strong value for efficient inference
- Multimodal capability on Step-5 (text, image, video understanding)
- Newer entrant — smaller track record than established frontier labs
- Documentation and support primarily in Chinese
Key weaknesses compared
Black Forest Labs
- Newer company with smaller ecosystem than Stable Diffusion
- Pro models require API access — no self-hosting for highest quality
- Less community fine-tuning ecosystem than SD
StepFun
- Newer entrant — smaller track record than established frontier labs
- Documentation and support primarily in Chinese
- Limited international ecosystem and third-party integrations
Provider category context
Black Forest Labs is a frontier lab, founded in 2024. StepFun is a frontier lab, founded in 2023. Both are frontier lab providers — the comparison is primarily about pricing, model selection, and feature differentiation within the same tier.
How to choose between them
Both Black Forest Labs and StepFun are frontier labs with proprietary models. Choose based on benchmark performance for your specific task: Black Forest Labs leads on flux 1.1 pro ultra: highest-quality commercial image generation available, while StepFun leads on step-5 preview is competitive with top chinese frontier models on reasoning benchmarks. For cost-sensitive workloads, compare the cheapest model tier from each provider in the pricing table above — the gap between efficient-tier models is often larger than between flagship models.