Seedance 2.5 API key: get one and send a first request
Create a Sume API key, POST to /v1/videos with model seedance-2.5, poll the job and download the file. One curl request, the auth rules and the fields to set.
To call Seedance 2.5 you need an API key and one request. Create the key at https://www.sume.com/dashboard/api-keys, then POST model: "seedance-2.5" to https://api.sume.com/v1/videos and poll the job until it completes.
BytePlus documents its own Seedance 2.5 key and endpoint in the ModelArk tutorial; this page covers the Sume route.
How do I send the first request?
Send exactly one auth header, either Authorization: Bearer $SUME_API_KEY or x-api-key. Always set duration, resolution and aspect_ratio so the job and its price are explicit.
curl -X POST https://api.sume.com/v1/videos \
-H "Authorization: Bearer $SUME_API_KEY" \
-H "Content-Type: application/json" \
-H "Idempotency-Key: seedance-25-first-001" \
-d '{
"model": "seedance-2.5",
"prompt": "A paper boat drifts down a rain-soaked street at dusk",
"duration": 8,
"resolution": "720p",
"aspect_ratio": "16:9"
}'How do I get the finished file?
The response is an async job. Poll GET /v1/videos/{id} about every 30 seconds; the docs say generation takes 30 seconds to several minutes. When the status is completed, download unsigned_urls[0].
Which errors should I expect first?
These are the 400s the docs and API code define for this route, read 2026-09-29.
| Cause | Response |
|---|---|
Sent seed, size or a non-empty provider.options | 400 unsupported_parameter |
| Aspect ratio not in the model's list, such as 3:2 | 400 unsupported_capability |
last_frame without a first_frame | 400 validation error |
| Both auth headers on one request | Rejected; send exactly one |
Sources
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