Flux 3 Klein Image Base Text To Image API Documentation

Flux 3 Klein Image Base Text To Image API Documentation

Playground

FLUX 3 Klein Base Text-to-Image generates images from text prompts, with 1K or 2K output and flexible aspect ratios. Ready-to-use REST inference API, best performance, no coldstarts, affordable pricing.

Features

FLUX 3 Klein Base Text-to-Image runs the full, non-distilled FLUX 3 Klein checkpoint for maximum fidelity (slower and priced higher than Distilled) from Black Forest Labs (5.6B open weights). Describe the image you want and get it back in seconds.

Why Choose This?

• Prompt-driven generation
  Full scene captions (framing, subject, background, lighting) give the best results.

• Text rendering
  Clear, readable text inside generated images.

• Layout control with bounding boxes
  Append a JSON list of boxes on a 0 to 1000 grid to place elements; in edits, refer to the n-th reference as <ref_image_n>.

• 1K and 2K output
  Choose 1k (~1 megapixel) or 2k (~4 megapixels) at 15 aspect ratios.

• Multiple output formats
  Export as jpeg, png, or webp.

• Seed control
  Use a fixed seed to reproduce a result, or -1 for random.

Parameters

Pricing

• 1k: $0.030 per image.
• 2k: $0.120 per image.

How to Use

1. Write a prompt — Describe the subject, composition, background, lighting, and style in full sentences.
2. Choose resolution and aspect ratio (optional).
3. Submit — Retrieve the finished image from the result.

Authentication

For authentication details, please refer to the Authentication Guide.

API Endpoints

Submit Task & Query Result

set -euo pipefail

export WAVESPEED_API_KEY="your-api-key"

REQUEST_BODY=$(cat <<'JSON'
{
  "prompt": "A cinematic ocean wave at sunrise, highly detailed",
  "aspect_ratio": "1:1",
  "resolution": "1k",
  "output_format": "jpeg"
}
JSON
)

# 1. Submit the prediction.
SUBMIT_RESPONSE=$(curl --silent --show-error --fail-with-body \
  -X POST "https://api.wavespeed.ai/api/v3/wavespeed-ai/flux-3-klein-image-base/text-to-image" \
  -H "Authorization: Bearer ${WAVESPEED_API_KEY}" \
  -H "Content-Type: application/json" \
  -d "${REQUEST_BODY}")

TASK=$(printf '%s' "${SUBMIT_RESPONSE}" | jq 'if type == "object" and has("data") then .data else . end')
PREDICTION_ID=$(printf '%s' "${TASK}" | jq -r '.id // empty')
if [ -z "${PREDICTION_ID}" ]; then
  printf 'Submission response did not contain a prediction id
' >&2
  exit 1
fi
RESULT_URL="https://api.wavespeed.ai/api/v3/predictions/${PREDICTION_ID}/result"

# 2. Poll until the prediction finishes.
while true; do
  RESPONSE=$(curl --silent --show-error --fail-with-body \
    "${RESULT_URL}" \
    -H "Authorization: Bearer ${WAVESPEED_API_KEY}")
  RESULT=$(printf '%s' "${RESPONSE}" | jq 'if type == "object" and has("data") then .data else . end')
  STATUS=$(printf '%s' "${RESULT}" | jq -r '.status // empty')

  case "${STATUS}" in
    completed) printf '%s\n' "${RESULT}" | jq '.outputs'; break ;;
    failed|cancelled|timeout|deleted) printf '%s\n' "${RESULT}" | jq . >&2; exit 1 ;;
    *) sleep 2 ;;
  esac
done

Parameters

Task Submission Parameters

Request Parameters

Response Parameters

Result Request Parameters

Result Response Parameters