Seedance 2.5 API Integration: A Practical Guide for Developers
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A Seedance 2.5 integration has two distinct operations: create a video task, then read that task until it reaches a terminal state. Treating generation as an ordinary request that immediately returns a finished file is the first design mistake to avoid.
This guide uses SeedRouter's documented Seedance 2.5 contract. The request shapes were checked on October 22, 2026. The examples explain submission and polling; they do not claim a paid generation was executed for this article.
Prepare the smallest useful Seedance 2.5 request
Start with text-to-video. It removes media accessibility and file-format questions while you establish authentication and task handling. Obtain an API key from SeedRouter, keep it on the server, and read the API base address from the current documentation into a server-side environment variable.
The public task collection path is /v1/contents/generations/tasks. A minimal explicit request body is:
{
"model": "dreamina-seedance-2-5",
"content": [
{
"type": "text",
"text": "A folded yellow umbrella rests on a stone bench. One slow camera push-in, soft overcast light, no cuts."
}
],
"resolution": "720p",
"ratio": "16:9",
"duration": 5,
"generate_audio": true
}These are SeedRouter's documented field names. Do not substitute a generic prompt field for the text item in content, or a made-up aspect_ratio field for ratio. Choosing a friendly label in your interface is fine; the submitted body must still use the API contract.
Send JSON with bearer authentication. A successful submission returns an id, which identifies the task. It is not a video URL and should not be passed to a video player.
Persist the ID before updating the interface
Store the task ID with the application's job record as soon as it arrives. Associate that record with the authenticated user, the validated request, and the submission time. The application should be able to recover the job after the page closes or the server restarts.
An application-generated job identifier and the remote task ID serve different purposes. Your job identifier connects the request to the customer and the interface. The remote task ID allows you to retrieve the generation. Keeping both avoids exposing your account's complete task history to a browser.
The user should see that the request was accepted, with a way to return to it. Do not report that the video is finished merely because submission returned successfully.
Poll the existing task, with a stopping rule
Read /v1/contents/generations/tasks/{id} with the same server-side credentials. SeedRouter documents queued and running as unfinished states, and succeeded, failed, and expired as terminal states.
For this API, polling every 10–20 seconds is the documented guidance. A successful task contains content.video_url. Failed or expired tasks contain an error object. Check the task status even when the HTTP response itself is successful: a successful status lookup can report a failed generation.
Use a local waiting deadline, but preserve the ID when that deadline passes. “This browser stopped waiting” and “the generation failed” are different outcomes. The interface should offer to resume checking the same task rather than quietly buy another render.
Submission timeouts need more care. If the connection breaks before an ID arrives, acceptance may be uncertain. Record that uncertainty and inspect recent tasks before another submission. Do not advertise automatic duplicate prevention unless your application has actually implemented and tested it.
Add media only after the text path is understood
Reference media enters content as URL-based items. A reference image has a type, a nested URL, and a role; a first frame is not interchangeable with a general visual reference.
For example, the role first_frame establishes the opening image. The role reference_image supplies a reference in the multimodal mode. SeedRouter's current documentation prohibits mixing first-frame mode with reference items, and requires an adaptive ratio for first-frame requests.
Validate the mode combination before submission, then validate the actual media. The URL must be accessible when generation begins. An expiring link, a login-protected image, or a URL that serves an HTML page instead of a file can fail even when the JSON is correct.
Do not add every media control on day one. Introduce one mode, document its limits, and verify it before extending the form. This keeps a bad reference file from being mistaken for a broken task implementation.
Keep the finished asset and the billing record separate
Once a video succeeds, save a durable copy if the product needs one. The generation service's result URL is a delivery location; your own retention requirements still need an explicit storage policy.
Record reported usage alongside the task, but do not invent a dollar field in the response. SeedRouter's public task data reports video-token usage; final charges are available in account usage history. A frontend estimate should be labelled as an estimate and tied to the chosen settings.
Failed requests are not charged on SeedRouter. A completed result remains billable even if an editor rejects its composition. Your application should preserve that distinction in both the job history and any customer-facing explanation.
Plan for a second service without assuming identical fields
If you later evaluate reAPI, read its model-specific request and task documentation. A shared model name does not make two services interchangeable at the JSON level.
Keep the service-specific conversion in one server module. The rest of the application can work with a small internal job record: submitted, working, ready, or failed, plus a result location when available. Preserve the original status and task ID internally so a simplified interface does not erase information needed for diagnosis.
Integration questions
Can the API key live in frontend code?
No. Keep it in server-only configuration. The browser should call your application, which validates the user and request before making the authenticated generation call.
Does polling create another paid generation?
Reading an existing task does not create a new generation. Posting another creation request does. Keep those operations separate in the code and interface.
Should a timeout immediately show “failed”?
No. Preserve an unfinished or uncertain state until the task itself reports a terminal outcome. Allow the same task to be checked again.
Finish the task lifecycle before adding controls
A dependable Seedance 2.5 API integration starts with a small, explicit request and ends with a recoverable result. Secure the key, persist the task ID, handle terminal states, and retain the asset. Additional model controls become much easier to add once those basics are observable and testable.