black-forest-labs

Black Forest Labs: FLUX.2 Klein 4B

black-forest-labs/flux.2-klein-4b

This native image model passed Jevrouter's production image smoke check: a 1024×1024 PNG was returned and the provider receipt charged $0.014 on September 21, 2026. That single result is historical evidence, not a guaranteed price for every request.

image

Try in Playground ↗

Provider-supported parameters

These are upstream capabilities. Jevrouter supports the subset described in the API contract; chat input is currently text only.

nseedaspect_ratiooutput_formatinput_references

Capabilities are imported from OpenRouter’s catalog. This does not mean every model has been independently tested by Jevrouter.

Catalog updated: 2026-09-22T08:51:50.371Z · Price version: cmub11ak300ukr82gd7py71jj:1

Image prices & options

Prices use each provider’s billing unit. We reserve a conservative amount and settle from the usage receipt, releasing unused balance.

Black Forest Labs

Usage	Unit	USD	Variant
output image	megapixel	$0.014	Default

{
  "n": {
    "type": "range",
    "min": 1,
    "max": 1
  },
  "seed": {
    "type": "boolean"
  },
  "aspect_ratio": {
    "type": "enum",
    "values": [
      "1:1",
      "4:3",
      "3:4",
      "3:2",
      "2:3",
      "16:9",
      "9:16",
      "21:9",
      "auto"
    ]
  },
  "output_format": {
    "type": "enum",
    "values": [
      "png",
      "jpeg"
    ]
  },
  "input_references": {
    "type": "range",
    "min": 0,
    "max": 4
  }
}

JEVROUTER INTEGRATION NOTES · REVIEWED 2026-09-22

What to check in your application

Megapixel billing can make the balance reservation larger than the final charge; unused funds are released.
Use the Images endpoint and stream:true for long calls through a proxy.

Start with the example below, then test representative inputs against your own acceptance criteria.

A real API result

A lime green paper boat on calm blue water, generated with FLUX.2 Klein 4B — September 21, 2026 · 1024 × 1024 PNG · actual provider receipt $0.014. Historical single-call evidence; current prices and options are listed above.

Make a request

Some models require reference images. Check the input_references range above. Images return base64 data and a usage receipt.

curl --no-buffer https://api.jevrouter.io/v1/images \
  -H "Authorization: Bearer $JEVROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d @- <<'JSON'
{
  "model": "black-forest-labs/flux.2-klein-4b",
  "prompt": "A small lime green paper boat floating on calm water, simple illustration, no text.",
  "n": 1,
  "stream": true
}
JSON

Plan your integration

Generate and save images with Python →Estimate this model’s cost →Budgets, request status and safe retries →

Related models to evaluate

Use identical inputs and scoring rules. No ranking is implied by this selection.

OpenAI: GPT Image 1 Mini Black Forest Labs: FLUX.2 Pro

Source: OpenRouter model catalog. Imported descriptions and capabilities are provider declarations, not independent benchmark results. Jevrouter currently uses OpenRouter as its managed upstream.