Black Forest Labs · Image API

FLUX Kontext

flux-kontext

Context-aware generation and image editing for controlled, iterative visual changes.

POST/v1/images/generations

Output count1–1

Reference imagesUp to 4

Resolution tiersRoute native

Generation

Generate with FLUX Kontext

Use ImgRouter's unified request contract and this model ID. The example uses recommended defaults from the route's current parameter guide.

cURL

curl https://api.imgrouter.com/v1/images/generations \
  -H "Authorization: Bearer $IMGROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: flux-kontext-generate-001" \
  -d '{
  "model": "flux-kontext",
  "prompt": "Editorial product photograph, precise materials, soft studio light",
  "size": "auto",
  "n": 1,
  "output_format": "png"
}'

Request body

modelstring · requiredUse flux-kontext.

promptstring · requiredGeneration or editing instruction between 1 and 5,000 characters.

sizestringSupported values: auto, 1:1, 4:3, 3:4, 16:9, 9:16, 3:2, 2:3, 21:9, 9:21.

ninteger · 1–1Number of output images. Defaults to 1 and cannot exceed 1.

output_formatstringSupported values: png, jpeg, webp.

reference_imagesstring[] · max 4Public HTTPS source images. Send this field to the edit endpoint.

Controls

Supported options

Aspect ratio or size

auto1:14:33:416:99:163:22:321:99:21

Output format

pngjpegwebp

Route notes

Context-aware generation and editing with up to four reference images.

One image is returned per request.

Use auto to follow the reference aspect ratio; without a reference it falls back to 1:1.

Reference workflow

Edit with reference images

Send public HTTPS source images with the same core controls. This route accepts up to 4 reference images.

POST/v1/images/edits

cURL

curl https://api.imgrouter.com/v1/images/edits \
  -H "Authorization: Bearer $IMGROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: flux-kontext-edit-001" \
  -d '{
  "model": "flux-kontext",
  "prompt": "Preserve the subject and composition. Change the scene to soft blue hour.",
  "size": "auto",
  "n": 1,
  "output_format": "png",
  "reference_images": [
    "https://example.com/reference.jpg"
  ]
}'

Describe both the intended change and the details that must remain consistent. Stable source URLs produce the most reliable edit requests.

Response

Read the completed output

Successful requests return completed image URLs and a request ID. Store the assets you need permanently; routed output URLs may expire.

200 · application/json

{
  "id": "req_01K4…",
  "object": "image.generation",
  "created": 1787424152,
  "data": [
    { "url": "https://static.imgrouter.com/images/req_01K4.webp" }
  ],
  "usage": { "images": 1 }
}

Use GET /v1/requests/{request_id} for reconciliation and GET /v1/balance for the authenticated key's current Credit position.