FLUX.1 Kontext [dev]

bfl/flux-2/kontext/dev

Flux 2 Kontext Dev by BFL - AI-powered image editing, style transfer, and transformation. Edit photos with natural language instructions, remove backgrounds, change styles, and enhance images effortlessly.

Try the model

Playground

Open playground

Input

Prompt(string)

The prompt to edit the image.

Image URL(string)

Upload

PNG, JPEG, WebP, or GIF · 20 MiB maximum

The URL of the image to edit. Max width: 14142px, Max height: 14142px, Timeout: 20s

This field is required.

Additional Settings More

Customize your input with more control.

Guidance scale (CFG)(number)

120

The CFG (Classifier Free Guidance) scale is a measure of how close you want the model to stick to your prompt when looking for a related image to show you. Range: 1 to 20.

Num Inference Steps(integer)

1050

The number of inference steps to perform. Range: 10 to 50.

Output Format(string)

Output format Allowed values: jpeg, png.

Resolution Mode(string)

Determines how the output resolution is set for image editing. - `auto`: The model selects an optimal resolution from a predefined set that best matches the input image's aspect ratio. This is the recommended setting for most use cases as it's what the model was trained on. - `match_input`: The model will attempt to use the same resolution as the input image. The resolution will be adjusted to be compatible with the model's requirements (e.g. dimensions must be multiples of 16 and within supported limits). Apart from these, a few aspect ratios are also supported. Allowed values: auto, match_input, 1:1, 16:9, 21:9, 3:2, 2:3, 4:5, 5:4, 3:4, 4:3, 9:16, 9:21.

Seed(integer)

The same seed and the same prompt given to the same version of the model will output the same image every time.

Result

Example

What would you like to do next?
Open original

Examples

Select an example to load its inputs and result into the playground.

Input

{
  "image": "https://static.sandbase.ai/examples/d4b6c66d-af5e-4af7-9d4e-4d82e9f249ac/input/8fde3e25-c086-4505-bd6d-4b7c824136b5.webp",
  "prompt": "Change the setting to a day time, add a lot of people walking the sidewalk while maintaining the same style of the painting"
}

Open result ↗

Human preference

Arena

Elo ratings from blind side-by-side votes, compared with other image and video models.

Rankings sourced from Artificial Analysis Arena

Leaderboard: Image Editing
Rank: #71 of 77
Elo: 883 ±21
Gap to #1: −316

Image-editing arena: people pick the better of two edits of the same image and instruction, without seeing the model names.

#66FLUX.1 Kontext [pro]Black Forest Labs916±19
#67FIBO EditBria915±19
#68SeedEdit 3.0ByteDance Seed901±20
#69LongCat ImageMeituan897±20
#70Qwen Image EditAlibabaOn SandBase889±20
#71FLUX.1 Kontext [dev]Black Forest LabsThis model883±21
#72HiDream-O1-Image-DevHiDream880±15
#73GLM-ImageZ AI824±22
#74BagelBytedance792±25
#75OmniGen V2VectorSpaceLab785±23

FLUX.1 Kontext [dev]

FLUX.1 Kontext [dev] edits a single image from an instruction: change objects, text, or style while keeping the rest consistent.

Fields

Field	Type	Default	Notes
`prompt`	string, required	—	Text instruction.
`image`	image URL, required	—	Image to edit. JPEG, PNG, or WebP URL.
`guidance_scale`	number 1–20	2.5	How strictly to follow the prompt.
`num_inference_steps`	integer 10–50	28	More steps add detail and time.
`output_format`	`jpeg` / `png`	`jpeg`	Output file format.
`resolution_mode`	`auto` / `match_input` / `1:1` / `16:9` / `21:9` / `3:2` / `2:3` / `4:5` / `5:4` / `3:4` / `4:3` / `9:16` / `9:21`	`match_input`	`match_input` keeps the input size; or choose a ratio.
`seed`	integer	random	Fix it to compare prompt changes.

Billing

$0.025 per image.

Request	Price
One image	$0.025

Failed runs are not charged.

Prompting

State the change and what must stay the same.

Limits

One input image.

Also on SandBase

Related: bfl/flux-2/dev/edit (FLUX.2, multi-image).

Start building

Send your first request

Submit this model through the SandBase Unified Run API.

Production API

Unified Run API endpoint

https://api.sandbase.ai/v1/run

Model ID

bfl/flux-2/kontext/dev

# The quoted heredoc keeps Unicode and shell metacharacters unchanged.
result=$(curl --fail-with-body --silent \
  -X POST "https://api.sandbase.ai/v1/run" \
  -H "Authorization: Bearer $SANDBASE_API_KEY" \
  -H "Content-Type: application/json" \
  --data-binary @- <<'SANDBASE_JSON'
{
  "model": "bfl/flux-2/kontext/dev",
  "image": "https://static.sandbase.ai/examples/bfl/flux-2/kontext/dev/input_image_0.webp",
  "prompt": "Change the setting to a day time, add a lot of people walking the sidewalk while maintaining the same style of the painting",
  "output_format": "jpeg",
  "guidance_scale": 2.5,
  "resolution_mode": "match_input",
  "num_inference_steps": 28
}
SANDBASE_JSON
)
run_id=$(printf '%s' "$result" | jq -r .id)
for attempt in $(seq 1 120); do
  status=$(printf '%s' "$result" | jq -r .status)
  case "$status" in completed|failed|timeout) break ;; esac
  sleep 2
  result=$(curl --fail-with-body --silent \
    -H "Authorization: Bearer $SANDBASE_API_KEY" \
    "https://api.sandbase.ai/v1/run/$run_id")
done
status=$(printf '%s' "$result" | jq -r .status)
[ "$status" = completed ] || { echo "Generation ended: $status" >&2; exit 1; }
printf '%s\n' "$result"

2. Authentication

Create a SandBase API key and set it in your server environment. All requests use Bearer authentication.

API key environment variable

export SANDBASE_API_KEY="YOUR_API_KEY"

Keep the key on your server. Do not expose it in browser code or commit it to a repository.

3. Queue

Submit a request

POST to /v1/run with this model ID and its inputs. The request example above includes submission and polling.

Fetch request status and result

Use the returned run ID to poll until the status is completed, failed or timeout. Read output only after completed.

Poll run status

curl "https://api.sandbase.ai/v1/run/$RUN_ID" \
  -H "Authorization: Bearer $SANDBASE_API_KEY"

4. Files

Hosted files

Pass a publicly accessible file URL in the model’s image, video or audio field. Supported formats and limits are shown beside each Playground input.

Uploading images

Use the upload or replace control on supported image fields in the Playground. Video URL fields accept a hosted driving video; they do not imply video-upload support.

5. Schema

Input

`seed`integer

The same seed and the same prompt given to the same version of the model will output the same image every time.

`image`stringrequired

The URL of the image to edit. Max width: 14142px, Max height: 14142px, Timeout: 20s

`prompt`stringrequired

The prompt to edit the image.

`output_format`string

Output format

Default: "jpeg"

Possible values: "jpeg", "png"

`guidance_scale`number

The CFG (Classifier Free Guidance) scale is a measure of how close you want the model to stick to your prompt when looking for a related image to show you.

Default: 2.5

Minimum: 1

Maximum: 20

`resolution_mode`string

Default: "match_input"

Possible values: "auto", "match_input", "1:1", "16:9", "21:9", "3:2", "2:3", "4:5", "5:4", "3:4", "4:3", "9:16", "9:21"

`num_inference_steps`integer

The number of inference steps to perform.

Default: 28

Minimum: 10

Maximum: 50

Request body

{
  "model": "bfl/flux-2/kontext/dev",
  "image": "https://static.sandbase.ai/examples/bfl/flux-2/kontext/dev/input_image_0.webp",
  "prompt": "Change the setting to a day time, add a lot of people walking the sidewalk while maintaining the same style of the painting",
  "output_format": "jpeg",
  "guidance_scale": 2.5,
  "resolution_mode": "match_input",
  "num_inference_steps": 28
}

Output

A completed run exposes its result in output. The following is the model’s saved example, not a new generation.

Example output JSON

[
  {
    "source": "BFL/FLUX schema mirror",
    "source_url": "https://docs.bfl.ai/flux_2/flux2_overview",
    "url": "https://static.sandbase.ai/examples/d4b6c66d-af5e-4af7-9d4e-4d82e9f249ac/output/4f32256b-22fa-4ee3-8a38-31d0fa466211.jpeg"
  }
]

FLUX.1 Kontext [dev]

Playground

Examples

Arena

FLUX.1 Kontext [dev]

Fields

Billing

Prompting

Limits

Also on SandBase

Send your first request

2. Authentication

3. Queue

Submit a request

Fetch request status and result

4. Files

Hosted files

Uploading images

5. Schema

Input

seedinteger

imagestringrequired

promptstringrequired

output_formatstring

guidance_scalenumber

resolution_modestring

num_inference_stepsinteger

Output

Flux 2 Dev Edit ↗

Flux 2 Flash Edit ↗

Flux 2 Flex Edit ↗

Flux 2 Klein 4B Edit ↗

Flux 2 Klein 9B Edit ↗

Flux 2 Max Edit ↗

`seed`integer

`image`stringrequired

`prompt`stringrequired

`output_format`string

`guidance_scale`number

`resolution_mode`string

`num_inference_steps`integer