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L402 API

Pay with Bitcoin, get AI results. Copy-paste the commands below.

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Before You Start

Lightning Wallet

Phoenix, Muun, Wallet of Satoshi, Alby, or any LN wallet. Agents: CLW

Terminal or Tool

A command line, Postman, or lnget (recommended)

Private & No Signup

No account, no subscription, no personal data. Pay only when you use it

Want to try this without a terminal? Use Image Analysis on the web — pay with any Lightning wallet, no setup needed.

Using the L402 Image Analysis API

Analyze and describe image content using AI vision models. Ask questions about any image.

API Endpoint: https://sats4ai.com/api/l402/analyze-image

Step 1: Initial Request

Send the image (base64 or data URI) with your question. You will receive a 402 Payment Required response.

curl -X POST https://sats4ai.com/api/l402/analyze-image \
-H "Content-Type: application/json" \
-d '{
  "image": "data:image/png;base64,iVBORw0KGgo...",
  "prompt": "What objects are in this image?"
}' \
-i

Expected Response Headers:

www-authenticate: L402 macaroon="<YOUR_MACAROON>", invoice="<LIGHTNING_INVOICE>"

Step 2: Pay the Lightning Invoice

Pay the invoice and save the preimage.

Step 3: Final Request

Send the exact same request with the Authorization header.

Important: The JSON payload must be identical to Step 1.

curl -X POST https://sats4ai.com/api/l402/analyze-image \
-H "Content-Type: application/json" \
-H "Authorization: L402 <YOUR_MACAROON_STRING_HERE>:<YOUR_PREIMAGE_HERE>" \
-d '{
  "image": "data:image/png;base64,iVBORw0KGgo...",
  "prompt": "What objects are in this image?"
}'

Expected Successful Response:

{ "content": "The image shows a cat sitting on a wooden table near a window..." }

Request Body Parameters

image: string (required)

Base64-encoded image or data URI (e.g. data:image/png;base64,...). If no prefix is provided, data:image/png;base64, is assumed.

prompt: string

Question to ask about the image. Default: "What's in this image?"

modelId: number or string (optional)

Omit for the best default model. See available models.