The Stability AI Platform API (the Developer Platform) is the hosted programming interface through which customers call Stability AI models for images, audio and 3D assets. It is the pay-as-you-go route: the customer buys credits in advance and each API request consumes a number of them. It sits under the Terms of Service, which cover “Stability’s Application Programming Interface” among the Services.[1]
Editions
The platform has no editions in the sense of tiers. It has endpoints, each with a credit price. The pricing page states that API usage is based on credits, that 1 credit equals USD 0.01, and that pricing is subject to change as models and infrastructure improve.[2] The catalog holds one row per endpoint (Platform API Stable Image Ultra is an example).
| Group | Service | Credits per request |
|---|---|---|
| Generate | Stable Image Ultra | 8 |
| Generate | Stable Diffusion 3.5 Large | 6.5 |
| Generate | Stable Diffusion 3.5 Large Turbo | 4 |
| Generate | Stable Diffusion 3.5 Medium | 3.5 |
| Generate | Stable Diffusion 3.5 Flash | 2.5 |
| Generate | Stable Image Core | 3 |
| Generate | SDXL 1.0 | from 0.9 |
| Upscale | Creative Upscaler / Conservative Upscaler / Fast Upscaler | 60 / 40 / 2 |
| Edit | Erase Object, Inpaint, Remove Background, Search and Recolor, Search and Replace | 5 each |
| Edit | Outpaint | 4 |
| Edit | Replace Background and Relight | 8 |
| Control | Structure, Sketch, Style Guide | 5 each |
| Control | Style Transfer | 8 |
| Audio | Stable Audio 3.0 and Stable Audio 2.5 | 8 each |
| 3D | Stable Fast 3D / Stable Point Aware 3D | 10 / 4 |
All figures are from the pricing page as retrieved on 2026-10-13.[2] The page describes Stable Audio 3.0 as generating up to six minutes of audio and Stable Audio 2.5 up to three minutes.[2]
Metrics
Credit. The credit is the only billing unit. A knowledge-base article explains that each endpoint has unique pricing based on the type of service and chosen parameters, such as image size or generation steps, so the same endpoint can cost different amounts. Where a request carries a “samples” parameter above one, the credits spent are multiplied by that value.[3] A reconciliation of credit consumption against invoices has to read the pricing page for the date of each request, because the credit price of an endpoint can change.[2]
Request rate. The API limits each key to 150 requests per 10 seconds. Exceeding it returns a 429 response followed by a 60 second timeout.[4] This is a technical limit, not a licence quantity, but it affects how an application provisions keys. The Terms forbid buying, selling or transferring API keys with a third party.[1]
Counting / floors
New developer platform accounts start with 25 free credits.[2] The public documents state no minimum purchase. Credits are bought in the Billing section after logging in to the platform, and credits for the platform are separate from other products: credits for Stable Assistant, for example, were exclusive to that product and could not be used on the Platform API.[5]
The Terms add four rules that matter for forecasting:
- Service credits are not currency, are not redeemable for money, are non-refundable and may be used only with the applicable Service.[1]
- Unused credits issued on or after the effective date of the Terms expire one year after purchase or issuance, unless otherwise specified.[1] The Terms in force were effective on 30 September 2026, so expiry applies to credits bought or issued from that date. Credits issued earlier may follow older terms.
- Credits may not be transferred, sold, gifted or traded, and evidence of such a transfer may end the balance and the account without a refund.[1]
- The balance is not a digital wallet or stored value account, and the customer is responsible for checking balance additions and deductions.[1]
Virtualization & partitioning
Not applicable. The service is hosted. An organisation partitions use by creating separate accounts or keys, but the Terms ask that login details are not shared and that the account holder is responsible for all activity, including by an end user who accesses the Services through the account.[1] If an account uses an employer’s email domain, the Terms say it may be linked to the organisation’s enterprise account, whose administrator may monitor and control it.[1]
Cloud / BYOL
Stability AI’s image and editing services are also sold through Amazon Bedrock. The Image Services launch announcement says nine editing tools are available there as managed API services, and names Mercado Libre and HubSpot as customers using the generation and editing services on Bedrock.[6] Customers buying this way should confirm whether Stability AI credits or the cloud provider’s billing and agreement apply (Cloud platform distribution).
Programs
Manual invoicing. Customers who anticipate more than USD 10,000 of spend per month can ask for manual invoicing through a support request.[7] (Manual invoicing above USD 10,000 monthly spend)
Data training opt-out. Platform API customers can set a preference to stop their content being used to train Stability AI models, using a setting that the knowledge base points to.[8] The Terms say that content may otherwise be used to improve services, with an opt-out available.[1]
Custom safeguards. Default content safeguards can be disabled only after the customer shows it can prevent violative content independently: a description of moderation practices, evidence such as case studies or certifications, and a signed agreement acknowledging responsibility for moderation.[9] The evaluation is Stability AI’s decision.
Third-party models. Where a service uses a third party’s model, the customer may not use outputs to train a model that competes with Stability AI or that third party.[1]
Deprecated endpoints. The hosted Stable Video Diffusion API was deprecated on 24 July 2025. The knowledge base directs customers to self-host the model after reviewing the licence terms on the Core Models page.[10] Inventory any application that still calls retired endpoints.
Contract terms
The Terms restrict four things for developers. A customer may not use the Services or outputs to develop, train, fine-tune or improve an AI model that competes with or replicates a Stability AI model unless approved in writing. It may not sell, resell, sublicense or distribute access to the Services or API except by letting end users use functionality solely through the customer’s own product as an integrated component. It may not crawl or scrape the Services, or use automated access except through the API within documented rate limits. And it may not knowingly remove watermarks, content credentials or provenance markings.[1] Stability AI assigns to the user its rights, if any, in outputs, and the user owns outputs to the extent permitted by law, with the Terms noting that other users may get similar results.[1] A separate written agreement controls over the Terms where they conflict.[1] The full list is in Stability AI Terms of Service and Acceptable Use Policy.
Audits and compliance
The Terms contain no audit right over API use, and billing is metered by Stability AI. Compliance risk lies in resale and integration: a reseller of generated images through its own product is within the integrated-component exception, while a service that hands out API access or keys is not. Keep records of which products embed the API, who holds keys, how credits are funded and when credits expire.
Out of scope
- Negotiated API commitments and enterprise agreements, which override the web terms.
- Prices of endpoints not on the pricing page and any price changes after 2026-10-13.
- Stable Assistant and DreamStudio credits, which belonged to other products. Stable Assistant was sunset on 1 October 2026.[11]
- Usage by cloud marketplace customers under their provider’s billing.