Veo 3.1 – Flux1 AI API

Veo 3.1 Fast and Quality, with text, frames and Fast reference-image generation.

POST/api/v1/generations

JSON requestAsynchronousOne video per request

Fast costs 200 credits per generation; Quality costs 550, for any supported duration. Reference images do not add an extra charge. Check credits_refunded to confirm a refund; unresolved submissions may require review.

Jump to request examples ↓

Authorization

Authorizationstringrequired

Bearer fx1_live_… — send your API key in the request header. Requires administrator approval and a completed paid purchase; new generations also require enough credits.

Idempotency-Keystringoptional

Use one unique value per generation and reuse it with the same body on retries. Printable ASCII, no spaces. A different body with the same key returns 409.

Maximum length: 128 characters

Manage API keys ↗

Request body

modelstringrequired

Use this exact model ID in the top-level request body.

veo-3-1

promptstringrequired

Describe the video, including desired audio. Must not be empty after trimming.

Maximum length: 2,000 characters

imagesstring[]optional

Public HTTPS image URLs. text: none; frames: one first frame or first/last pair; reference: one to three references. Maximum 2,048 characters per URL.

Maximum items: 3

modestringoptional

Fast costs 200 credits per generation; Quality costs 550. The same per-generation price applies to 4, 6 and 8 seconds; it is not a per-second price.

Default: fast

fastquality

generation_typestringoptional

Select input behavior explicitly. reference requires Fast mode and an 8-second duration.

Default: text

textframesreference

aspect_ratiostringoptional

Landscape or portrait output. Auto cropping is not offered.

Default: 16:9

16:99:16

resolutionstringoptional

720p output. Higher-resolution upgrades are not included or exposed.

Default: 720p

720p

durationnumberoptional

Exactly 4, 6 or 8 seconds. reference mode only supports 8. Native audio is enabled by the provider; no audio toggle is exposed.

Default: 8

Range: 4–8. See field description for allowed values.

Response & next step

A successful submission returns 202 and a generation id. Poll GET /api/v1/generations/{id} every 2–3 seconds until the status is succeeded or failed.

Read the result URL from output.video.url. Download it before expires_at (30 days after storage). On failure, inspect error and credits_refunded.

Generation lifecycle →Error reference →

Build your request

200 credits / 8s video

ModeSpeed / quality

Examples only. Run on your server with your API key.

# Set FLUX1_IDEMPOTENCY_KEY once per generation; reuse it on retries.
curl --request POST 'https://flux1.ai/api/v1/generations' \
  --header "Authorization: Bearer $FLUX1_API_KEY" \
  --header 'Content-Type: application/json' \
  --header "Idempotency-Key: ${FLUX1_IDEMPOTENCY_KEY:?Set a unique key for this generation}" \
  --data '{
  "model": "veo-3-1",
  "prompt": "Ocean waves wash onto a beach at sunrise, gentle surf sounds",
  "mode": "fast",
  "generation_type": "text",
  "aspect_ratio": "16:9",
  "resolution": "720p",
  "duration": 8
}'

202 · POST /api/v1/generations

{
  "id": "gen_example",
  "status": "queued",
  "model": "veo-3-1",
  "media_type": "video",
  "credits": 200,
  "credits_refunded": false,
  "input": {
    "prompt": "Ocean waves wash onto a beach at sunrise, gentle surf sounds",
    "mode": "fast",
    "generation_type": "text",
    "aspect_ratio": "16:9",
    "resolution": "720p",
    "duration": 8
  },
  "output": null,
  "expires_at": null,
  "content_expired": false,
  "error": null,
  "created_at": "2026-09-07T08:00:00.000Z",
  "completed_at": null
}

Model notes

The provider's veo3 and veo3_fast identifiers currently select Veo 3.1, so the public ID is veo-3-1. This does not claim to serve the original Veo 3 model.
Fast costs 200 credits per generation; Quality costs 550, for 4, 6 or 8 seconds. Prices are per request, not per second. Output is 720p with native audio; higher-resolution upgrades are not included.
text requires no images. frames requires one first frame or a first/last pair. reference requires 1–3 images, Fast mode and 8 seconds.
Provider fallback and automatic prompt translation are disabled. This API does not expose Lite, extension, watermark text, an audio toggle or custom callbacks.
Success is returned after the final video is stored in Flux R2. Download before expires_at, 30 days after storage. Refunds restore the original credit buckets, and credits_refunded confirms completion.

Provider contract: KIE Veo generation.