Example request body:

{
  "text": "The patient reported persistent headaches over the past two weeks, with no improvement from over-the-counter medication.",
  "targetLanguage": "Spanish",
  "sourceLanguage": "English"
}

Step 1: Initial Request (get Invoice)

Send your text. You will receive a 402 Payment Required response with a Lightning invoice priced by text length.

curl -X POST https://sats4ai.com/api/l402/translate-text \
-H "Content-Type: application/json" \
-d '{
  "text": "Hello, how are you today?",
  "targetLanguage": "French"
}' \
-i

Expected response headers:

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

Step 2: Pay the Lightning Invoice

Pay the invoice with any Lightning wallet. Save the preimage your wallet provides after payment.

Step 3: Re-send with Payment Proof

Send the exact same request again with the Authorization header.

The JSON payload must be identical to Step 1.

curl -X POST https://sats4ai.com/api/l402/translate-text \
-H "Content-Type: application/json" \
-H "Authorization: L402 <YOUR_MACAROON>:<YOUR_PREIMAGE>" \
-d '{
  "text": "Hello, how are you today?",
  "targetLanguage": "French"
}'

Successful response: {"translatedText": "...", "sourceLanguage": "English", "targetLanguage": "French"}

Easier: Use lnget

lnget handles the full L402 flow automatically — invoice, payment, and re-request in one command.

lnget -X POST https://sats4ai.com/api/l402/translate-text \
  --json '{"text":"Hello, how are you?","targetLanguage":"Japanese"}'

Python Example

import requests

payload = {
    "text": "The contract shall be governed by the laws of the State of New York.",
    "targetLanguage": "German",
    "sourceLanguage": "English"  # optional — auto-detected if omitted
}

# Step 1 — get invoice
r = requests.post("https://sats4ai.com/api/l402/translate-text",
    json=payload,
    headers={"Content-Type": "application/json"})
# r.status_code == 402
# Parse macaroon and invoice from r.headers["www-authenticate"]

# Step 2 — pay invoice with your Lightning wallet, get preimage

# Step 3 — re-send with auth
r2 = requests.post("https://sats4ai.com/api/l402/translate-text",
    json=payload,
    headers={
        "Content-Type": "application/json",
        "Authorization": "L402 <macaroon>:<preimage>"
    })
result = r2.json()
print(result["translatedText"])
print(result["targetLanguage"])   # "German"
print(result["sourceLanguage"])   # "English"

Request Parameters

Use Cases

• Translate legal contracts or medical documents without uploading to cloud services
• AI agents that need to communicate across languages
• Translate user-generated content for multilingual apps
• Privacy-sensitive document translation (no data stored)
• Batch translation of product descriptions or support articles