Stability AI vs Upstage: Token Pricing, Speed & Intelligence
Full comparison of Stability AI and Upstage — live token pricing, latency, throughput, context window, strengths, weaknesses, and best use cases. Rates sourced from public APIs — verify before use.
Stability AI
Stable Diffusion 3.5 Large and Stable Image Ultra — open-weight image generation
Stability AI is the creator of Stable Diffusion, the most widely deployed open-weight image generation model family. The 2026 API offers Stable Diffusion 3.5 Large (highest quality), SD 3.5 Medium (balanced), and Stable Image Ultra for photorealistic output. All SD 3.5 models are open-weight and available for self-hosting. Stability AI also offers Stable Video Diffusion for short video generation.
Upstage
Solar Pro 4, Solar Pro 3, Solar Pro 2 — Korean frontier models with strong multilingual performance
Upstage is a Korean AI company offering the Solar model family via API. Solar Pro 4 is the current flagship, with Solar Pro 3 and Solar Pro 2 available at lower price points. The Solar models are known for strong multilingual performance, particularly in Korean and English, and competitive pricing relative to their capability tier. Pricing is published at upstage.ai/pricing.
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Live token pricing
Strengths and weaknesses
Stability AI
Upstage
Key differentiators
Stable Diffusion 3.5 models are open-weight and self-hostable — enabling the largest fine-tuning and LoRA ecosystem of any image generation model family, with full control over the generation pipeline.
Korean-built Solar models with strong multilingual performance and competitive frontier-tier pricing — Solar Pro 4 at $0.30/$1.20 per 1M tokens.
Frequently asked questions
Stability AI FAQs
What is Stable Diffusion 3.5?
Stable Diffusion 3.5 is Stability AI's latest generation of open-weight text-to-image models. SD 3.5 Large offers the highest quality; SD 3.5 Medium is a balanced option for production use. Both are available for self-hosting.
How does Stability AI compare to FLUX?
FLUX 1.1 Pro generally outperforms SD 3.5 on photorealism and prompt adherence benchmarks. However, SD 3.5 has a much larger community ecosystem of fine-tuned variants and LoRAs, making it more flexible for specialised use cases.
Can I self-host Stable Diffusion 3.5?
Yes. SD 3.5 Large and Medium weights are publicly available under the Stability AI Community License. You can run them on any GPU with sufficient VRAM — SD 3.5 Medium requires ~8GB VRAM; SD 3.5 Large requires ~24GB.
Upstage FAQs
What is Upstage Solar?
Upstage Solar is a family of LLMs from Korean AI company Upstage. Solar Pro 4 is the current flagship, with Solar Pro 3 and Solar Pro 2 at lower price points. See upstage.ai/pricing for current rates.
How much does Upstage Solar cost?
As of October 2026: Solar Pro 4 $0.30/$1.20 per 1M tokens, Solar Pro 3 $0.15/$0.60, Solar Pro 2 $0.15/$0.60. See upstage.ai/pricing for current rates.
Is Upstage good for Korean language tasks?
Yes. The Solar model family is developed by a Korean AI company and shows strong performance on Korean-language benchmarks, making it a top choice for Korean NLP workloads.
Provider resources
Stability AI — Stable Diffusion 3.5 Large and Stable Image Ultra — open-weight image generation
Stability AI is the creator of Stable Diffusion, the most widely deployed open-weight image generation model family. The 2026 API offers Stable Diffusion 3.5 Large (highest quality), SD 3.5 Medium (balanced), and Stable Image Ultra for photorealistic output. All SD 3.5 models are open-weight and available for self-hosting. Stability AI also offers Stable Video Diffusion for short video generation.
Stable Diffusion 3.5 models are open-weight and self-hostable — enabling the largest fine-tuning and LoRA ecosystem of any image generation model family, with full control over the generation pipeline.
Upstage — Solar Pro 4, Solar Pro 3, Solar Pro 2 — Korean frontier models with strong multilingual performance
Upstage is a Korean AI company offering the Solar model family via API. Solar Pro 4 is the current flagship, with Solar Pro 3 and Solar Pro 2 available at lower price points. The Solar models are known for strong multilingual performance, particularly in Korean and English, and competitive pricing relative to their capability tier. Pricing is published at upstage.ai/pricing.
Korean-built Solar models with strong multilingual performance and competitive frontier-tier pricing — Solar Pro 4 at $0.30/$1.20 per 1M tokens.
Key strengths compared
Stability AI
- Open-weight SD 3.5 models — self-host on any GPU cloud
- Largest community ecosystem of fine-tuned variants and LoRAs
- Stable Image Ultra for photorealistic output
- Image quality trails FLUX 1.1 Pro and Midjourney on photorealism benchmarks
- Company has faced financial challenges and leadership changes
Upstage
- Solar Pro 4: competitive frontier-tier pricing at $0.30/$1.20 per 1M tokens
- Strong multilingual performance — Korean and English
- Three-tier model family: Solar Pro 4, 3, and 2 for different cost/quality trade-offs
- Smaller global ecosystem than OpenAI or Anthropic
- Limited model variety beyond the Solar family
Key weaknesses compared
Stability AI
- Image quality trails FLUX 1.1 Pro and Midjourney on photorealism benchmarks
- Company has faced financial challenges and leadership changes
- SD 3.5 adoption slower than FLUX in the community
Upstage
- Smaller global ecosystem than OpenAI or Anthropic
- Limited model variety beyond the Solar family
- Less documentation in English than major US providers
Provider category context
Stability AI is a frontier lab, founded in 2020. Upstage is a frontier lab, founded in 2020. 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 Stability AI and Upstage are frontier labs with proprietary models. Choose based on benchmark performance for your specific task: Stability AI leads on open-weight sd 3.5 models — self-host on any gpu cloud, while Upstage leads on solar pro 4: competitive frontier-tier pricing at $0.30/$1.20 per 1m tokens. 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.