Overview
Stability AI is the company behind Stable Diffusion, the open-weight image model family that kicked off the modern generative-image wave, and today it sells those models plus audio and 3D generation through a single developer API at platform.stability.ai. The appeal is control: unlike closed services, the Stable Diffusion line can be self-hosted, fine-tuned with LoRAs, and bent into custom pipelines, which is why it remains the backbone of countless AI art tools and community models. Through the API you get a menu of image services — from the legacy SDXL 1.0 to the newer Stable Diffusion 3.5 Large and the flagship Stable Image Ultra — alongside Stable Audio for sound generation and Stable Fast 3D for turning a single photo into a 3D asset. Billing is credit-based: one credit equals one U.S. cent, new accounts get a small free balance, and each generation costs a few credits depending on the model. In our evaluation Stability AI is the most flexible route for developers who need programmable, license-aware image generation, but the recent SD3.5 licensing terms (free only under $1M annual revenue, with stricter commercial and redistribution rules) have pushed some teams back to the fully open SDXL, and per-credit pricing can outrun a flat subscription once volume climbs.
Key Features
- Stable Diffusion model family — From open SDXL 1.0 to SD 3.5 Large and Stable Image Ultra, covering speed, quality, and fine-tunability trade-offs.
- Credit-based, per-image pricing — Pay only for what you generate; 1 credit = $0.01, with a free starter balance for testing.
- Audio and 3D alongside images — Stable Audio for sound and Stable Fast 3D for single-image-to-3D in the same API surface.
- Rich editing and control services — Inpaint, outpaint, remove background, style transfer, and structure or sketch guidance for precise composition.
- Open weights for self-hosting — Run supported models locally or fine-tune them, avoiding per-call costs at scale.
Pricing
| Plan | Price | For |
|---|---|---|
| Free starter credits | 25 credits (~$0.25) | New accounts, try before buying |
| SDXL 1.0 (API) | ~$0.009 / image | Cheapest, huge community LoRAs |
| SD 3.5 Large (API) | ~$0.065 / image | Highest quality, research license |
| Stable Image Ultra | ~$0.08 / image | Flagship photoreal detail |
| Audio / 3D | from 4 to 26 credits | Stable Audio, Stable Fast 3D |
Comparison
Compared to Midjourney, Stability AI is developer-first and open-weight, ideal for programmable pipelines, while Midjourney remains the easier, better-looking choice for artists who just want great images. Against Leonardo AI, both target creator workflows, but Leonardo adds a polished web UI and asset management that Stability lacks. Versus Getimg, Stability’s API is the lower-level engine many of those consumer apps are built on, trading convenience for raw flexibility.