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by Black Forest Labs

Fast FLUX edits that keep faces and poses intact

black-forest-labs/flux-2-klein-9b/text-to-imageFrom 2 creditsper image · $0.02
Try in PlaygroundGet API key
  • Up to 2K
  • Up to 3 reference images
  • 9 aspect ratios
  • Create Image
  • Edit Image

About FLUX.2 Klein 9B

FLUX.2 [klein] 9B is Black Forest Labs' small, fast image model, released on 15 January 2026. One model both generates and edits, with up to three reference images, 1k or 2k output and nine aspect ratios. Most renders came back in 15 to 35 seconds in our tests.

Call it with the model name black-forest-labs/flux-2-klein-9b/text-to-image on POST /jobs/createTask, from 2 credits per image ($0.02). New accounts get 30 free credits to try it in the Playground first.

Introduction

FLUX.2 [klein] 9B Text to image is Black Forest Labs' small, fast image model, released on 15 January 2026, generating pictures from a written prompt.

Choose a mode by starting material

What you haveMode
a written briefFLUX.2 Klein 9B Text to image
images to changeFLUX.2 Klein 9B Edit

Key features

Fast enough to iterate

It is the quick end of the FLUX.2 line.

Text and look sheets

Quote a header or a sign and it is usually rendered as written. One prompt can also lay out several looks of the same person in a grid. Neither is guaranteed on every seed.

Request parameters

ParameterRequiredDescription
seedNoReuse the same number to get a repeatable result. ≥ 0 · ≤ 2147483647
promptYesDescribe the subject, setting, light and style in plain sentences.
resolutionNoOutput size. Bigger sizes look sharper and cost more. 1k · 2k · Default: 1k
aspect_ratioNoThe shape of the frame: wide, square or tall. 1:1 · 16:9 · 9:16 · 4:3 · 3:4 · 3:2 · 2:3 · 21:9 · 9:21 · Default: 1:1

Pricing

Prices are in credits, the same credits you use on the website (1 credit = $0.01). The hold is taken when the task is accepted and settled to the actual charge when it finishes; failed tasks are refunded.

OptionCredits per image≈ USD
resolution 1K1.65$0.017
resolution 2K1.83$0.018

Each task is rounded up to whole credits, so one run at the lowest tier costs 2 credits per image ($0.02).

For an exact number before you run, send the same body to POST /jobs/quote.

Use cases

Batches of variations

Many takes on one idea, to pick from or to feed into an edit.

Character look sheets

Several outfits of one character in a single frame.

Drafts for larger models

Settle on composition here before spending on a bigger model.

Prompt guide & pro tips

Say what the people wear

Garment, cut and how it sits. Without it the model fills in clothing by itself.

Quote text and keep it short

A few words per line render best. If a word is wrong, change the seed.

Do not rely on exact hex colours

A hex value gets you the right direction, not the exact shade.

Try three seeds

Small models vary. Hands and fine text improve with a second or third try.

API quick start

Call the FLUX.2 Klein 9B API in three steps

  1. Create an API key. Sign in to PopNow and create a key in the API console. Keys start with sk-popnow- and use the same credits as the website.
  2. Send the request. POST /jobs/createTask with model black-forest-labs/flux-2-klein-9b/text-to-image and an input object that follows the parameter table. The response returns a task ID straight away.
  3. Get the result. Poll GET /jobs/recordInfo with the task ID, or pass a callBackUrl and we post the result to it. Download the output links when the task succeeds.
# 1. Create the task. Keep the Idempotency-Key if you retry after a network error.
export IDEMPOTENCY_KEY="$(uuidgen)"
curl -X POST https://api.popnow.ai/api/v1/jobs/createTask \
  -H "Authorization: Bearer $POPNOW_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $IDEMPOTENCY_KEY" \
  -d '{
  "model": "black-forest-labs/flux-2-klein-9b/text-to-image",
  "input": {
    "prompt": "A ceramic teapot on a linen cloth, soft window light, muted palette",
    "aspect_ratio": "1:1",
    "resolution": "1k"
  }
}'

# 2. Copy data.taskId from the response, then poll until state is succeeded, failed, canceled or expired.
TASK_ID="TASK_ID_FROM_RESPONSE"
curl "https://api.popnow.ai/api/v1/jobs/recordInfo?taskId=$TASK_ID" \
  -H "Authorization: Bearer $POPNOW_API_KEY"

Replace the prompt and any links with your own. The API tab has the response, polling and callback reference.

FLUX.2 Klein 9B API questions

How much does the FLUX.2 Klein 9B API cost?

FLUX.2 Klein 9B starts at 2 credits ($0.02) per image with Create Image, its cheapest task. Prices by option: 1K 1.65 credits per image, 2K 1.83 credits per image. Credits are the same as on the website (1 credit = $0.01), new accounts get 30 free credits, and failed tasks are refunded.

What is the model name for FLUX.2 Klein 9B in the API?

Put black-forest-labs/flux-2-klein-9b/text-to-image for Create Image; black-forest-labs/flux-2-klein-9b/edit for Edit Image in the model field of POST /jobs/createTask.

Can it write text into images?

Short, quoted text usually works: our lookbook render spelled its header and all four captions correctly, and a neon sign came out clean on the third seed we tried. It is not reliable every time, so plan to try a few seeds.

Does it follow hex colour codes?

Roughly. A requested sand-coloured background came out in the right direction but not as the exact value, so do not use it where a precise brand colour is required.

How many reference images can I use?

One to three in an edit. Mention them in your prompt in the order you uploaded them.

What are the limits of the FLUX.2 Klein 9B API?

Resolutions: 1K · 2K; Aspect ratios: 1:1 · 16:9 · 9:16 · 4:3 · 3:4 · 3:2 +3; Prompt length (characters): 5,000. Requests outside these limits are rejected before anything is charged.

Can I try FLUX.2 Klein 9B without writing code?

Yes. The Playground runs FLUX.2 Klein 9B on your PopNow credits, needs no API key, and shows the matching code for every run.

All FLUX models

FLUX.2 Pro and Max render text and fine detail more reliably; Klein 9B is much faster and cheaper per image.

More about FLUX.2 Klein 9B