LnBot.L402.AspNetCore 0.2.0

LnBot.L402.AspNetCore

L402 Lightning payment middleware for ASP.NET Core — paywall any API in one line. Built on ln.bot.

Protect ASP.NET Core routes behind L402 paywalls with middleware, [L402] attributes, or endpoint filters. Includes the LnBot.L402 client package.

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.AspNetCore

This includes the client package (LnBot.L402) — no need to install both.

Quick Start

Middleware pipeline

using LnBot;
using LnBot.L402;

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

var app = builder.Build();

app.UseL402Paywall("/api/premium", new L402Options
{
    Price = 10,
    Description = "API access",
});

app.MapGet("/api/premium/data", () => Results.Ok(new { data = "premium content" }));
app.MapGet("/api/free/health", () => Results.Ok(new { status = "ok" }));

app.Run();

Controller attribute

using LnBot.L402;

[ApiController]
[Route("api/[controller]")]
public class WeatherController : ControllerBase
{
    [L402(Price = 50, Description = "Weather forecast")]
    [HttpGet("forecast")]
    public IActionResult GetForecast()
        => Ok(new { forecast = "sunny" });
}

Minimal API endpoint filter

app.MapGet("/api/premium/data", () => Results.Ok(new { data = "premium" }))
   .AddEndpointFilter(new L402EndpointFilter(price: 10, description: "API access"));

Dynamic pricing

app.UseL402Paywall("/api/dynamic", new L402Options
{
    PriceFactory = context =>
    {
        if (context.Request.Path.StartsWithSegments("/api/dynamic/bulk"))
            return Task.FromResult(50);
        return Task.FromResult(5);
    }
});

How It Works

The middleware makes two SDK calls:

• client.L402.CreateChallengeAsync() — creates an invoice + macaroon when a client needs to pay
• client.L402.VerifyAsync() — verifies an L402 authorization token when a client presents one

All L402 logic — macaroon creation, signature verification, preimage checking — lives in the ln.bot API. Zero crypto dependencies.

Requirements

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

Related

• LnBot.L402 — Client-side auto-pay handler
• LnBot — The .NET SDK this package is built on
• @lnbot/l402 — TypeScript equivalent

Links

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

License

MIT