Is Stability AI API free?

How to prepare a first image API request

Use one request from a local API client or server before connecting generation to an application. This keeps the starter balance predictable and makes errors easier to diagnose.

1. Create the developer account

   Open Stability’s developer platform. The getting-started guide explicitly links 25 free credits to creating an account through Google sign-in. Its key-management article uses broader new-account wording; check the balance actually granted instead of assuming every signup method receives the same offer.

2. Create and protect a key

   Open your profile’s API Keys view and use the plus control to create a key. Store it in a server-side environment variable or secret manager. Never paste it into browser JavaScript, a public repository or a shared screenshot. Rotate and delete a key if exposed.

3. Choose Core and prepare the request

   Use the official Stable Image Core request sample. It sends a POST with a Bearer authorization header and multipart form data. Choose Accept: image/* for binary output; let your HTTP client build the multipart Content-Type boundary rather than typing it manually.

4. Set a small, deliberate test

   Put the exercise below in the prompt field. Set aspect_ratio to 16:9 and output_format to webp. Check Core’s current price and your balance before sending once. A style preset or fixed seed is optional; start without them so you know which input you changed.

5. Check the response before saving

   On a successful image response, save the binary body as a WebP file and open it locally. On an error, inspect the status and error response instead of saving error text with an image extension. Record the endpoint, prompt and settings, then check the remaining balance.

Example: one header illustration for a reading app prototype

An imaginary reading app gives you a simple way to test composition without uploading a user’s photo or confidential design. Generate only the illustration; keep headings and buttons in your application’s ordinary interface. This prompt has not been run.

• Does the downloaded file open as a real image? A 200 response and a saved filename are not substitutes for inspecting the file.
• Does the book remain recognizable in a narrow mobile header? Check cropping and small-object edges before generating another variation.
• Keep headings and buttons as accessible HTML or editable layout text. Generated lettering should not carry the app’s navigation or factual instructions.
• Save the prompt, aspect ratio and format alongside the result. Change one instruction for a retry so you can tell what improved the composition.
• Keep the API key out of the frontend. Before exposing generation to visitors, add server-side validation, authentication for private operations, rate limits and a spending cap appropriate to that application.

What can 25 starter credits cover?

At the checked rates, Core costs 3 credits per successful generation and Ultra costs 8. A full 25-credit balance could therefore fund eight successful Core results with 1 credit left, or three Ultra results with 1 left, if nothing else consumes the balance. These are budget calculations, not measured results or an offer of recurring free images.

One credit is priced at $0.01, and the getting-started guide lists $1 for 100 purchased credits. Other endpoints have different costs: the 40-credit Conservative Upscaler and 60-credit Creative Upscaler each exceed the entire starter balance. Do not assume every advertised service can be tried with 25 credits.

The Core reference says failed generations are not charged. That does not make blind retry loops a good idea: repeated successful requests consume credits, and a network timeout may leave you unsure whether the previous job completed. Check the response and account balance before retrying.

Starter credits do not refill daily. The current terms say unused service credits issued on or after September 30, 2026 expire one year after issuance or purchase unless otherwise specified. Check your own grant conditions and balance; no expiration date for an individual account is guessed here.

Fix the request before spending on another attempt

Core documents invalid-parameter errors, content-moderation rejection, rate limiting and server failures. Read the error response first. For a malformed request, check the required prompt, multipart encoding and allowed field values. For a moderation rejection, use a permitted brief rather than trying to bypass the controls.

If the key is rejected, verify its environment-variable setup and whether it is still active. Avoid printing the key or the full authorization header in logs. A lack of credits and a broken request are different problems; buying credits does not fix an invalid parameter.

For rate limits or temporary failures, use bounded retries with a delay and a way to stop. This page does not benchmark latency or promise that a retry will succeed. Keep a local placeholder illustration while the prototype’s API integration is being checked.

Separate hosted API access from model licenses and output rights

Stability’s current service terms cover the API and assign its rights in compliant outputs to users to the extent permitted by law. You remain responsible for input permissions, third-party rights and acceptable use; ownership wording is not a promise of an exclusive or legally risk-free image. Applicable supplemental or model terms also need review.

The terms prohibit implying an AI output was human-generated and restrict removing applied watermarks or provenance markings without permission. A provider showcase or a clean-looking preview does not establish that every API output has no marks. Inspect the actual file and preserve applicable provenance.

Hosted starter credits and self-hosted model weights are different routes. The latter require your own hardware, setup and applicable model license; API credits are not free compute for running a downloaded model. The image API is also distinct from the provider’s audio apps and cloud-partner billing.

When to choose Dreamina instead

Consider Dreamina for a personal image experiment when you want to choose a model and edit a result in a browser rather than build an authenticated API request.

Dreamina has its own daily-credit eligibility, paid finishing options and uncertain commercial wording. Its browser balance does not transfer to Stability, and it does not establish a developer API quota. Choose the workflow you actually need before comparing credit numbers.