Wan 3 API

When to use it

Wan 3 is the premium tier: longer clips, selectable resolution up to 1080p, a generated soundtrack and the strongest prompt following of the three video models. It is also the slowest and the most expensive per second, so the usual pattern is to iterate on wan-2.2 and render the final take on wan-3.

It is a hosted model — the request is relayed to the upstream provider and polled until the clip lands — which is why it accepts no LoRAs and no negative prompt. Everything else about the job is identical: same endpoint, same job object, same webhook.

• Pick the resolution per request: 480p for previews, 1080p for the final render
• Prompt sound as well as motion; the audio track follows the description
• Register a webhook_url — clips take minutes, longer at 1080p and 15 s

Generate a clip

curl https://api.fastgencloud.com/v1/videos/generations \
  -H "Authorization: Bearer $FASTGEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
      "model": "wan-3",
      "image": "https://example.com/still.jpg",
      "prompt": "slow dolly in, she looks up from the book, café chatter and rain outside",
      "duration": 10,
      "resolution": "1080p"
    }'

Parameters

model

wan-3

image

start frame — https URL or data URI

prompt

optional motion + sound description, up to 2000 characters

duration

5, 8, 10 or 15 seconds

resolution

480p, 720p (default) or 1080p

seed

optional integer for reproducible output

webhook_url

strongly recommended for video

Unfiltered and uncensored

This endpoint applies no content filter. Your prompt, negative prompt, reference images and LoRAs reach the model verbatim, nothing is rewritten or injected, and outputs are not scanned or blocked. What your product allows is your call.

The one automatic rule is the minor-safety floor: a prompt that pairs a minor or age reference with sexual content is refused for that request only. Nothing else is filtered and the account is never touched by moderation.

How the API works

Every generation is a job. The POST returns 202 with a job id immediately, so your request thread is never blocked on a GPU. You then either poll GET /v1/jobs/{id} or register a webhook_url and receive a signed callback when the job finishes.

Send an Idempotency-Key header and a retried request replays the original job instead of charging you twice. Your wallet is debited when the job is submitted and refunded automatically if it fails.

curl https://api.fastgencloud.com/v1/jobs/$JOB_ID \
  -H "Authorization: Bearer $FASTGEN_API_KEY"

Pricing and billing

Pricing is prepaid and usage-based: you top the wallet up with a card and each job debits it. There is no subscription, no per-seat cost, and no monthly minimum.

Images above 1 megapixel are billed pro rata by pixel count — a 1.5 MP image costs 1.5x the listed rate. Failed jobs are refunded in full, automatically.