LnBot.L402 0.2.0

LnBot.L402

L402 Lightning payment client for .NET — auto-pay any L402-protected API with HttpClient. Works in console apps, background services, MAUI — anything with HttpClient. Built on ln.bot.

Looking for server-side middleware? See LnBot.L402.AspNetCore.

What is L402?

L402 is a protocol built on HTTP 402 Payment Required. It enables machine-to-machine micropayments over the Lightning Network — ideal for API monetization, AI agent tool access, and pay-per-request data feeds.

Install

dotnet add package LnBot.L402

Quick Start

With DI (ASP.NET Core, Worker Services)

using LnBot;
using LnBot.L402;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddSingleton(new LnBotClient("key_..."));

builder.Services.AddHttpClient("paid-apis")
    .AddL402Handler(new L402ClientOptions
    {
        MaxPrice = 100,
        BudgetSats = 50_000,
        BudgetPeriod = BudgetPeriod.Day,
    });

var app = builder.Build();

app.MapGet("/proxy", async (IHttpClientFactory factory) =>
{
    var http = factory.CreateClient("paid-apis");
    var data = await http.GetStringAsync("https://api.example.com/premium/data");
    return Results.Ok(data);
});

Console App (no ASP.NET Core)

using LnBot;
using LnBot.L402;
using Microsoft.Extensions.DependencyInjection;

var services = new ServiceCollection();
services.AddSingleton(new LnBotClient("key_..."));
services.AddSingleton<ITokenStore, MemoryTokenStore>();
services.AddHttpClient("paid-apis").AddL402Handler();

var provider = services.BuildServiceProvider();
var http = provider.GetRequiredService<IHttpClientFactory>().CreateClient("paid-apis");

// Auto-pays any 402 responses transparently
var response = await http.GetStringAsync("https://api.example.com/premium/data");
Console.WriteLine(response);

Options

Custom Token Store

Implement ITokenStore for Redis, file system, or any persistence layer:

public class RedisTokenStore : ITokenStore
{
    public Task<L402Token?> GetAsync(string url) { /* ... */ }
    public Task SetAsync(string url, L402Token token) { /* ... */ }
    public Task DeleteAsync(string url) { /* ... */ }
}

services.AddSingleton<ITokenStore, RedisTokenStore>();

Header Utilities

using LnBot.L402;

L402Headers.ParseAuthorization("L402 mac_base64:preimage_hex");
L402Headers.ParseChallenge("L402 macaroon=\"abc\", invoice=\"lnbc1...\"");
L402Headers.FormatAuthorization("mac", "pre");
L402Headers.FormatChallenge("mac", "lnbc1...");

How It Works

The L402DelegatingHandler intercepts HttpClient responses:

1. If the response is 402, it reads the WWW-Authenticate header
2. Calls client.L402.PayAsync() to pay the Lightning invoice via the ln.bot API
3. Retries the request with the Authorization: L402 <macaroon>:<preimage> header
4. Caches the token for future requests to the same URL

Zero crypto dependencies — all L402 logic lives in the ln.bot API.

Requirements

• .NET 8+
• An ln.bot API key — create a wallet to get one

Related

• LnBot.L402.AspNetCore — Server-side middleware
• LnBot — The .NET SDK this package is built on
• @lnbot/l402 — TypeScript equivalent

Links

• ln.bot — website
• Documentation
• L402 specification
• GitHub

License

MIT