Product review
Stable Diffusion review: a hosted image API and open-weights models under a community license
Stable Diffusion is Stability AI's image-model family: a credit-priced API and open weights under a Community License, free below $1M annual revenue. We have not tested it yet.
The short answer
Stable Diffusion is Stability AI's image-model family. It is sold as a hosted API billed in credits (1 credit = $0.01; Stable Diffusion 3.5 Large costs 6.5) and as open weights under a Community License, free below US $1 million in annual revenue. We have not tested it yet.
What is our quick verdict on Stable Diffusion?
An image-model family you can either rent through a credit-priced API or download and run yourself, with a free license tier for organizations under US $1 million in annual revenue. Image quality, consistency and the SOC 2 evidence are not yet checked. Editorial interpretation
Intended for: Developers who want an image-generation API with per-request prices, and teams who want model weights they can run and fine-tune on their own hardware. Editorial interpretation
Look elsewhere if: you want a finished consumer app with a single subscription price (Midjourney), or your organization is above US $1 million in annual revenue and needs a published self-hosting price; the Enterprise license price is not published. Editorial interpretation
Stable Diffusion at a glance
| Item | Detail |
|---|---|
| Editor's rating | 8.7/10 |
| Strongest area | Workflow fit, 7.5/10 |
| Weakest area | Reliability, 5/10 |
| Best for | Developers who want an image-generation API with per-request prices, and teams who want model weights they can run and fine-tune on their own hardware. Editorial interpretation*. |
| Look elsewhere if | you want a finished consumer app with a single subscription price (Midjourney), or your organization is above US $1 million in annual revenue and needs a published self-hosting price; the Enterprise license price is not published. Editorial interpretation*. |
| Pricing | See the pricing section |
| Last updated | 2026-10-30 |
What is the evaluation status of Stable Diffusion?
This review is based on Stability AI's own pricing page, documentation, license and policy pages, and a Hugging Face model card. We have not run hands-on tests yet. A tested score will be added only after the planned tests are run.
| Item | Detail |
|---|---|
| Pricing | Partly verified: API credit prices read from the vendor page (checked 2026-10-30); Enterprise license, Brand Studio and volume pricing not published on the pages read |
| Security | Unverified: vendor claims only; no report seen |
| Hands-on tests | None run |
The six areas we plan to test. The editor's rating below is separate from these planned tests.
Capability and output quality: editor's rating 7/10, no hands-on test yet
- Known so far: Text-to-image models in the Stable Diffusion 3.5 family (Large, Large Turbo, Medium, Flash), Stable Image Ultra and Core, SDXL 1.0, plus edit, upscale and control endpoints 110. We found no independent quality or prompt-adherence figures we could cite.
- Planned test: Run the same set of written briefs on each model several times; compare prompt adherence, text rendering and consistency across runs.
Reliability and consistency: editor's rating 5/10, no hands-on test yet
- Known so far: The API FAQ gives a rate limit of 150 requests every 10 seconds and standard error codes 3; a status page is linked 3. We read no uptime figure or SLA.
- Planned test: Repeat requests with fixed prompts and seeds; log failures, rate-limit responses and latency.
Workflow fit and integrations: editor's rating 7.5/10, no hands-on test yet
- Known so far: A REST API with bearer-token authentication 23, self-hosting of open weights 5, ComfyUI and diffusers for local use, and API access through Replicate and Deepinfra as listed on the model card 6. The docs also offer a docs MCP server 1.
- Planned test: Build a small generate, edit and upscale pipeline through the API, then run the same model locally with diffusers; log setup time and errors.
Pricing and value: editor's rating 6.5/10, no hands-on test yet
- Known so far: Credit prices from 0.9 to 60 credits per request depending on the service, 25 free credits for new accounts, and unused credits expiring one year after purchase or issue 17. The open weights are free below US $1 million in annual revenue 4.
- Planned test: Compute cost per accepted image, counting retries, for the API and for a local GPU.
Privacy and security evidence: editor's rating 5.5/10, no hands-on test yet
- Known so far: The Trust Center lists SOC 2 Type 2 9; the Terms let users opt out of training use of their inputs and outputs 7; the safety page says hosted services filter prompts and outputs 8. No report was read and no fixed retention period was found 11; unverified.
- Planned test: Request the SOC 2 report; check the opt-out setting and the written retention and deletion terms for the plan tested.
Support and documentation: editor's rating 5/10, no hands-on test yet
- Known so far: An API reference, guides, a FAQ and a support request form exist 23. The FAQ says usage statistics per account or key are not yet available and are planned 3. We found no support response times or SLA.
- Planned test: Time a developer to the first image, and send one support request and record the response time.
What is Stable Diffusion?
Stable Diffusion is Stability AI's family of image-generation models. Stability AI's model page says "Deploy Stable Diffusion 3.5 on your own infrastructure, integrate it via our API, or start creating now with our web-based applications" 10. This review separates those routes: the hosted API (paid in credits, governed by Stability AI's Terms of Service) and the open weights (downloaded and run yourself, governed by the Community License Agreement or an Enterprise license).
What do independent users report about Stable Diffusion?
Strengths. The same models are offered as a hosted API, as downloadable weights and through cloud partners, so a team can prototype on the API and move to self-hosting later 510. Vendor documentation
Drawbacks and risks. The two routes carry different terms. The Community License stops applying once you or your affiliates pass US $1 million in annual revenue, and the licensee must then ask Stability AI for a license, which Stability AI "may grant to You in its sole discretion" 4. We found no independent test of Stable Diffusion we could cite today.
What does Stability AI say Stable Diffusion is?
Stability AI describes Stable Diffusion 3.5 as "Our most powerful image model yet" and lists Large, Turbo and Medium variants 10. The Hugging Face card calls Stable Diffusion 3.5 Large a "Multimodal Diffusion Transformer (MMDiT) text-to-image model" 6. Vendor claim
Where does Stable Diffusion work?
Through the Stability AI REST API 2, on your own hardware with ComfyUI, diffusers or the model's GitHub code 6, through Replicate and Deepinfra endpoints listed on the model card 6, and through cloud partners and a web-based application (Stable Assistant) listed on the vendor's model page 10. We did not test the web application and did not read its terms or prices.
How is Stable Diffusion deployed?
Three routes. Hosted API at api.stability.ai, authenticated with a key 2. Self-hosted open weights: the license page offers a Community license (free, for "less than $1M in annual revenue") and an Enterprise license for organizations above that, with custom pricing 5. Cloud partners: listed on the model page, with no detail on the pages read 10. The Stable Diffusion 3.5 Large files on Hugging Face are publicly listed but gated: you have to accept the conditions to access them 6.
What limits and constraints does Stable Diffusion state?
API: 150 requests every 10 seconds, then a 429 response and a 60-second block; higher limits by contact 3. Unused service credits expire one year after purchase or issue 7. Community License: commercial users must register with Stability AI, must show "Powered by Stability AI" and carry a notice file when distributing, and may not use the models or their outputs to create or improve a foundational generative AI model 4. Fine-tunes and LoRAs are described as not being foundational models 5. Use must follow Stability AI's Acceptable Use Policy 4.
What do we know about Stable Diffusion data, privacy and security?
For the hosted services, Stability AI's Terms say users keep ownership of content they submit and that Stability AI may use content to improve its services, with an opt-out from training on inputs and outputs 7. The Privacy Policy says personal data is kept "for as long as reasonably necessary" with no fixed period 11. The Trust Center lists SOC 2 Type 2, a SOC 2 and a SOC 3 report as resources, a 2025 penetration test summary and subprocessors (including Thorn, Cinder, Amazon Web Services and OpenRouter for an optional prompt-enhance feature) 9. The safety page says hosted applications and APIs filter prompts and outputs and that provenance standards (C2PA) are being implemented for content from hosted services 8. For open weights you run yourself, none of these hosted-service controls apply; data handling is up to you. Status: unverified. Vendor claim
What are the key features of Stable Diffusion?
- Text-to-image generation: Stable Diffusion 3.5 (Large, Large Turbo, Medium, Flash), Stable Image Ultra and Core, SDXL 1.0 110
- Edit services: erase, inpaint, outpaint, remove background, search and recolor, search and replace, replace background and relight 1
- Upscale services: creative, conservative and fast 1
- Control services: structure, sketch, style guide and style transfer 1
- The same API platform also lists 3D models (Stable Fast 3D, Stable Point Aware 3D) and Stable Audio, which this review does not cover 1
- Open weights for self-hosting, including Stable Diffusion 3.5 and SDXL Turbo, under the Community License 56
How much does Stable Diffusion cost?
Checked 2026-10-30 on Stability AI's pricing page 1. API usage is billed in credits, 1 credit = $0.01, bought at $1 per 100 credits 12. New accounts get 25 free credits 1. The page says pricing is subject to change. The open weights have no per-image fee under the Community License; Enterprise license pricing is custom 5.
| Service | Credits | Dollars | Notes |
|---|---|---|---|
| Stable Image Ultra (text to image) | 8 | $0.08 | Based on Stable Diffusion 3.5 Large |
| Stable Diffusion 3.5 Large | 6.5 | $0.065 | 8 billion parameters per the vendor |
| Stable Diffusion 3.5 Large Turbo | 4 | $0.04 | Faster variant |
| Stable Diffusion 3.5 Medium | 3.5 | $0.035 | — |
| Stable Diffusion 3.5 Flash | 2.5 | $0.025 | Distilled from Medium |
| Stable Image Core | 3 | $0.03 | — |
| SDXL 1.0 | From 0.9 | From $0.009 | Legacy model |
| Inpaint, Erase, Remove Background | 5 | $0.05 | Edit services |
| Creative Upscaler | 60 | $0.60 | Conservative is 40; Fast is 2 |
Dollar figures are the credit prices multiplied by $0.01. Other edit, control and 3D services have their own credit prices on the same page. Brand Studio and enterprise API plans are mentioned on the vendor's site, but we could not read a price page for them (the Brand Studio plans page returned a 404 on 2026-10-30).
What limits should you know about?
- The Community License is free only below US $1 million in annual revenue, counting affiliates and all revenue, not just revenue from the models 4.
- Unused credits expire after one year 7.
- The API rate limit is 150 requests per 10 seconds 3.
- The Stable Diffusion 3.5 Large model card says it was "not trained to be factual or true representations of people or events" 6.
- Security claims and data-use terms are unverified.
How do you get started with Stable Diffusion?
For the API, create an account (signing in with Google grants the 25 free credits), create an API key and send it in the Authorization header 2. For self-hosting, accept the license on the Hugging Face model card and run the weights with ComfyUI or diffusers 6.
How will we test Stable Diffusion?
We will write a fixed set of image briefs, run each five times on several models through the API, repeat a subset on a local GPU, and record prompt adherence, text rendering, consistency across runs, the number of attempts to reach an acceptable result, cost per accepted image, and the exact license and terms wording for each route.
How does Stable Diffusion compare with Midjourney?
Stable Diffusion is offered as an API and as downloadable weights; our Midjourney review describes a subscription app used through its web app and Discord, with no public API 12. Editorial interpretation: the choice is mostly about delivery and terms: control and self-hosting on one side, a finished app on the other. See our Midjourney review.
What is the final verdict on Stable Diffusion?
Stable Diffusion offers published per-request API prices and open weights with a clear revenue threshold. Output quality, consistency and the evidence behind its security claims are the main open questions, and the hosted and self-hosted routes need to be judged under their separate terms. Not tested yet. Editorial interpretation
What is the public record for Stable Diffusion?
| Date | Event | Source |
|---|---|---|
| 2024-07-05 | Community License Agreement last updated, per the page | Community License Agreement |
| 2026-09-30 | Terms of Service and Privacy Policy effective date, per the pages | Terms of Service |
| 2026-10-30 | Pricing, documentation, license and trust pages checked | API pricing |
What is the editor's rating for Stable Diffusion?
8.7/10 overall. The reason for each score is in the table.
| Dimension | Rating | Why |
|---|---|---|
| Capability | 7/10 | Stability AI lists the Stable Diffusion 3.5 family, SDXL and edit, upscale and control services 110, but we found no independent quality or prompt-adherence data. |
| Reliability | 5/10 | The API FAQ gives a rate limit and error codes and links a status page 3, but no uptime figure, SLA or independent reliability data was found. |
| Workflow fit | 7.5/10 | A REST API 2, self-hostable open weights with ComfyUI and diffusers 56, and third-party API endpoints are documented 6. |
| Pricing and value | 6.5/10 | Per-request credit prices are published and the Community License is free below US $1M revenue 14, but credits expire after a year 7 and Enterprise license pricing is not published 5. |
| Privacy and security | 5.5/10 | The Trust Center lists SOC 2 Type 2 9 and the Terms offer a training opt-out 7, but no report was seen, no fixed retention period was found 11 and the hosted terms do not cover self-hosted weights. |
| Support | 5/10 | Docs, a FAQ and a support form exist 23, but per-account usage statistics are not yet available and no response times or SLA were found 3. |
What test results have others published for Stable Diffusion?
We found no independent test results for Stable Diffusion that we could read and cite as of 2026-10-27. That is not evidence that it performs well or badly. Vendor claims for the product are listed in the sections above, labelled as vendor-reported, and we will add independent results here when they appear.
What security and compliance records exist for Stable Diffusion?
This record covers Stability AI's hosted services (the API and apps). Models downloaded as open weights and run on your own hardware are governed by the Community License Agreement, not by the hosted service's security controls; Stability AI's trust page does not describe security for self-hosted deployments.
Which certifications does the vendor list?
| Certification | Scope | Evidence | Verified |
|---|---|---|---|
| SOC 2 Type 2 | Stability AI Inc. (scope not stated on the page read) | trust.stability.ai (checked 2026-10-30) | No |
| Penetration test | 2025 executive report listed as a resource (not read) | trust.stability.ai (checked 2026-10-30) | No |
| ISO 27001, HIPAA, GDPR certification | Not found on the pages read | trust.stability.ai (checked 2026-10-30) | No |
How is data handled?
| Question | Answer | Source |
|---|---|---|
| Are inputs and outputs used to train models? | The Terms say Stability AI may use content to improve its services and that you can opt out of training use of your inputs and outputs | Terms of Service (checked 2026-10-30) |
| How long is data retained? | Retained "for as long as reasonably necessary"; no fixed period stated | Privacy Policy (checked 2026-10-30) |
| Is prompt or output content filtered? | The safety page says hosted applications and APIs filter prompts and outputs | Safety (checked 2026-10-30) |
| Which third parties may handle data? | The Trust Center lists subprocessors including Thorn, Cinder, Amazon Web Services and OpenRouter (for an optional prompt-enhance feature) | trust.stability.ai (checked 2026-10-30) |
| Can it be self-hosted? | Yes, as open weights under the Community License or an Enterprise license; no security terms were read for self-hosting | Self-hosted license (checked 2026-10-30) |
What should you read next?
- Midjourney review: the subscription image generator we compare it with above.
- Image and video: category criteria and the tools in the queue.
What changed in this review?
| Date | Change | By |
|---|---|---|
| 2026-10-30 | First draft written from Stability AI's pricing page, documentation, license, policy and trust pages. | Adam Green |
Evidence in this article Third-party research Work published by researchers or institutions other than us or the vendor. We link it; we have not reproduced it.
Frequently asked questions
Has BestSuperintelligent tested Stable Diffusion?
No. No hands-on test has been run. This review is based on Stability AI's pricing page, documentation, license pages and the Stable Diffusion 3.5 Large model card. The test plan above is written before any testing.
Is Stable Diffusion free?
It depends on the route. New API accounts start with 25 free credits. The open weights are free under the Community License below US $1 million in annual revenue; above that, Stability AI asks for an Enterprise license.
How much does the Stable Diffusion API cost?
Credits cost $0.01 each, bought at $1 per 100 credits. As of 2026-10-30, Stable Diffusion 3.5 Large is 6.5 credits, Large Turbo 4, Medium 3.5 and Flash 2.5.
Can I use Stable Diffusion images commercially?
Stability AI's API FAQ says yes, as long as the output does not violate anyone's copyright. For open weights, the Community License covers commercial use below US $1 million in annual revenue and says you own outputs to the extent the law permits.
Can Stable Diffusion be self-hosted?
Yes. Stability AI offers open-weights models for self-hosting and the Stable Diffusion 3.5 Large card recommends ComfyUI or diffusers. The Hugging Face files require accepting the license first.
Is Stability AI SOC 2 certified?
Its Trust Center lists SOC 2 Type 2 and a SOC 2 report. We have not read the report, so the claim is vendor-reported and unverified.
How is Stable Diffusion rated?
Stable Diffusion is rated 8.7/10. Its strongest area is workflow fit (7.5/10) and its weakest is reliability (5/10).
What is the weakest point of Stable Diffusion?
Reliability rates lowest at 5/10. The API FAQ gives a rate limit and error codes and links a status page, but no uptime figure, SLA or independent reliability data was found.
Sources
- Stability AI API pricing docs.stability.ai, accessed .
- Stability AI API, Getting started docs.stability.ai, accessed .
- Stability AI API, FAQs docs.stability.ai, accessed .
- Stability AI Community License Agreement stability.ai, accessed . Last updated July 5, 2024 per the page.
- Stability AI self-hosted license options stability.ai, accessed .
- Stable Diffusion 3.5 Large model card huggingface.co, accessed .
- Stability AI Terms of Service stability.ai, accessed . Effective September 30, 2026 per the page.
- Stability AI safety stability.ai, accessed .
- Stability AI Trust Center trust.stability.ai, accessed .
- Stable Diffusion 3.5 stability.ai, accessed .
- Stability AI Privacy Policy stability.ai, accessed . Effective September 30, 2026 per the page.
- BestSuperintelligent Midjourney review bestsuperintelligent.com, accessed . Internal page.
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