L402 API Access

Use AI tools by paying with Bitcoin. No signup. No API keys.

Pay with Bitcoin. Get AI Results.

Access 30+ AI services using Lightning Network micropayments. No signup, no monthly subscription, no data collection. Just Sats.

Not a developer? You can use all of these tools directly on the web — browse available tools and pay with any Lightning wallet, no setup needed.

New: full reference for L402, MCP, WebLN, async jobs, error codes, dedup, auto-routing and CORS — see /docs.

⚡

No Signup

No accounts, no emails, no passwords

💰

Pay Per Use

No subscriptions. Only pay when you use it

🔒

Private

No personal data collected. Ever

₿

Bitcoin Native

Lightning payments settle in seconds

How It Works

Send Your Request

Call any API endpoint with your data. You'll get back a Lightning invoice to pay.

Pay with Lightning

Pay the invoice with any Lightning wallet. Takes seconds, costs pennies.

Get Your Result

Re-send the same request with your proof of payment. Done.

Building an autonomous agent? MCP handles payment negotiation inline — no header parsing or retry logic needed. See why MCP vs raw HTTP matters or go straight to the MCP docs.

Services & Pricing

All prices in Satoshis (1 Sat ~ $0.001 USD). Click any service for full instructions.

Service	What It Does	Price
Image Generation	Create images from text prompts	100-200 Sats/image
Text Generation	AI chat and text completion	5-15 Sats minimum
Video Generation	Generate videos from text	300-550 Sats/sec
Video from Image	Animate images into video	100 Sats/sec
Music Generation	Full songs with AI vocals, BPM/key control	300 Sats/song
Text to Speech	3 tiers: OmniVoice Global (602+ langs), Inworld Max Premium (#1 ELO), Minimax Studio (voice cloning)	10-100 chars/sat
Speech Transcription	Transcribe audio to text	10 Sats/minute
Image Analysis	Ask AI about any image	21 Sats/image
3D Model Generation	Turn photos into 3D models	350 Sats/model
File Conversion	Convert between file formats	100 Sats/file
OCR / Text Extraction	Extract text from PDFs and images	10 Sats/page
SMS Service	Send text messages globally	varies by country
Automated Phone Call	Place calls with TTS or audio playback. Pricing scales with duration and destination.	varies by country & duration
AI Phone Call	Send an AI voice agent to make a two-way phone call with transcript and analysis	~150-250 Sats/call
Send Fax	Send a fax worldwide — PDF (from URL) or typed text. No fax machine required	500 Sats (≤10 pages) +50/page
Receive Fax	Open a 24h window to receive a fax at our shared number, delivered to your email. Optional OCR	500 Sats (+200 OCR)
Email Sending	Send a one-off email to any address — no account, no domain setup, no monthly fee	200 Sats/email
Voice Cloning	Clone a voice from an audio sample for use with TTS	7,500 Sats
Image Editing	Edit images with AI — background removal, style transfer, object removal	200-450 Sats/edit
PDF Merge	Merge multiple PDFs into a single document	100 Sats
HTML to PDF	Convert HTML or Markdown to PDF documents	50 Sats
Document Translation	Translate text across 119 languages with ultra-fast AI	From 4 Sats
Receipt OCR	Extract structured data from receipts and invoices	50 Sats/page
Background Removal	Remove background from any image, get transparent PNG	5 Sats/image
Image Upscaling	Upscale images 2x or 4x with neural super-resolution	5 Sats/image
Face Restoration	Restore blurry or damaged faces to sharp, natural quality	5 Sats/image
NSFW Detection	Classify image safety (normal/suggestive/explicit). Falcons.ai — 100x cheaper than an LLM	2 Sats/image
Object Detection	Detect and locate objects by name with bounding boxes. Grounding DINO (ECCV 2024)	5 Sats/image
Smart Object Removal	Remove objects by describing what to remove — no mask needed. Grounding DINO + Bria Eraser	15 Sats/image
Photo Colorization	Colorize black-and-white or grayscale photos with vivid, natural color. DDColor (ICCV 2023)	5 Sats/image
Image Deblurring	Fix blurry or out-of-focus photos. NAFNet (ECCV 2022, SOTA). Real pixel reconstruction	20 Sats/image

Easiest Way: Use lnget

lnget is Lightning Labs' official CLI for L402 APIs — handles request, payment, and authentication in a single command. Install: go install github.com/lightninglabs/lnget/cmd/lnget@latest

Copy and paste any of these examples:

Generate an image:

lnget -X POST https://sats4ai.com/api/l402/generate-image \
  -d '{"prompt":"A cat on the moon"}'

Generate text:

lnget -X POST https://sats4ai.com/api/l402/generate-text \
  -d '{"input":[{"role":"user","content":"Explain Bitcoin"}]}'

Transcribe audio:

lnget -X POST https://sats4ai.com/api/l402/transcribe-audio \
  -d '{"file":"<base64-audio>","type":"transcription"}'

lnget auto-pays the Lightning invoice, caches the token, and returns the result. Subsequent calls to the same endpoint reuse the cached token.

L402 tokens expire after 10 minutes — pay the invoice and submit your request within that window. Media URLs (images, video, audio) expire after 2 hours. Download or display them promptly.

Building autonomous agents? CLW is a Bitcoin wallet built for AI agents — lets them receive, hold, and spend sats programmatically.

Auto-Paying L402 Libraries

These open-source libraries handle L402 payment automatically — your code makes a normal HTTP request, the library detects the 402 challenge, pays the invoice, and retries with proof. No payment logic needed.

npm install l402-requests

l402-requests — three lines of TypeScript. Supports Strike, LND, NWC (Alby Hub, CoinOS), with built-in budget controls and spending logs.

pip install l402-requests

l402-requests — same auto-paying flow for Python.

.NET

dotnet add package l402-dotnet

l402-dotnet — same auto-paying flow for .NET.

import { get } from 'l402-requests';

// That's it. The library pays the Lightning invoice automatically.
const response = await get("https://sats4ai.com/api/l402/generate-text", {
  method: "POST",
  body: JSON.stringify({ input: [{ role: "user", content: "Explain Bitcoin" }] })
});

Manual Flow (Step by Step)

If you prefer to handle payments yourself (or want to understand how L402 works under the hood):

Send your request to the API endpoint

You'll get a 402 Payment Required response with a Lightning invoice and a macaroon (access token).

Pay the Lightning invoice

Use any Lightning wallet (Phoenix, Muun, Wallet of Satoshi, Alby, etc.). For autonomous AI agents, see CLW. Save the preimage (proof of payment) your wallet gives you.

Re-send the exact same request with your payment proof

Add this header: Authorization: L402 <macaroon>:<preimage>

Click any service below for the exact copy-paste commands.

Refunds & Error Handling

All services use prepaid invoices — payment settles instantly before the AI task runs. If the task fails after payment, you get an automatic refund via LNURL-withdraw.

What happens on failure

If the AI provider returns an error after you've paid, the response includes a refund object with an lnurl_withdraw field — a bech32-encoded LNURL-withdraw URL you can use to pull your sats back.

For agents

Check response.error_code to decide how to recover, then parse response.refund.lnurl_withdraw to claim the refund programmatically with any LNURL-compatible wallet or library.

Error codes

TIMEOUT — retry later or try a different model

CONTENT_FILTERED — rephrase prompt (safety filter triggered)

RATE_LIMITED — wait and retry

INVALID_INPUT — fix parameters

SERVICE_ERROR — try different model or contact support

For humans

On the web dashboard, the LNURL-withdraw link is displayed as a QR code you can scan with any Lightning wallet.

Rate limiting

The first 2 failures per 15-minute window receive a full refund. After that, a 2 sat routing fee is deducted from each refund to discourage abuse. This resets every 15 minutes.

// Example error response with refund
{
  "error": "Image generation timed out",
  "error_code": "TIMEOUT",
  "refund": {
    "charge_id": 12345,
    "refund_amount": 200,
    "lnurl_withdraw": "lnurl1dp68gurn8ghj7...",
    "status": "pending"
  }
}

What is L402?

L402 is a standard that lets you pay for API access with Bitcoin instead of signing up for accounts and handing over personal data. It combines:

Lightning Network — instant Bitcoin payments (fractions of a penny)
Macaroons — tamper-proof access tokens (like a receipt)

The result: pay-per-use AI with full privacy. No accounts, no API keys, no credit cards, no monthly bills. You only pay for what you use, and we never know who you are.

Learn more about the L402 protocol

For Developers: All endpoints and pricing are available as machine-readable JSON at /.well-known/l402-services, /api/l402/models, /api/models/routing, and /api/discover (semantic tool search). View L402 code examples (Python, Node.js, curl) or the MCP server repo on GitHub. Found a bug? Report it on GitHub or join the discussions.