L402Server.AspNetCore 0.1.2

L402Server.AspNetCore

ASP.NET Core middleware for L402. Drop one line into any ASP.NET API to charge per-request Lightning payments. Built on L402Server — Lightning Enable handles invoices, macaroons, and payment verification; your API stays where it is.

Install

dotnet add package L402Server.AspNetCore

Target: .NET 8.0+.

30-second example

using L402Server.AspNetCore;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddL402AspNetCore(opts =>
{
    opts.ApiKey = builder.Configuration["LightningEnable:ApiKey"]!;
});

var app = builder.Build();
app.UseRouting();
app.UseL402();
app.MapControllers();
app.Run();

Then mark any controller action with [L402(PriceSats = 100)] and that endpoint is gated behind a 100-sat L402 payment:

[ApiController]
[Route("api/premium")]
public class PremiumController : ControllerBase
{
    [HttpGet("weather")]
    [L402(PriceSats = 100)]
    public IActionResult Weather() => Ok(new { temp = 72 });
}

That's it. The middleware handles:

• Issuing 402 Payment Required with a Lightning invoice on unauthenticated requests
• Verifying Authorization: L402 <macaroon>:<preimage> on retries
• Stashing the verified credential in HttpContext.Items[L402HttpContextKeys.VerificationResult]

Endpoints without [L402] pass through ungated.

Pricing patterns

Per-route attributes (compile-time prices)

[HttpGet("forecast"), L402(PriceSats = 100)]
public IActionResult Forecast() => Ok(...);

[HttpGet("premium-llm"), L402(PriceSats = 500, Description = "GPT-4 backed")]
public IActionResult PremiumLlm() => Ok(...);

Global flat price (gates everything mounted under the middleware)

app.UseL402(opts => opts.DefaultPriceSats = 100);

Function-form pricing (variable per request)

app.UseL402(opts =>
{
    opts.PriceSelector = ctx => ValueTask.FromResult(
        ctx.Request.Query["model"] == "premium" ? 500 : 100);
});

Resolution order: PriceSelector > [L402(PriceSats)] attribute > DefaultPriceSats. If none → request passes through ungated.

Verified credential on downstream handlers

[HttpGet("weather"), L402(PriceSats = 100)]
public IActionResult Weather(HttpContext ctx)
{
    var result = (VerificationResult)ctx.Items[L402HttpContextKeys.VerificationResult]!;
    _logger.LogInformation("Served {Resource} for {Sats} sats ({Hash})",
        result.Resource, result.AmountSats, result.PaymentHash);
    return Ok(new { temp = 72 });
}

Configuration

Two integration modes

Lightning Enable supports two integration shapes:

• Proxy mode — point Lightning Enable at your API URL; we forward authenticated requests on your behalf.
• Native mode — install this middleware in your existing API. Lightning Enable handles payment; your API handles everything else. This middleware is the Native mode for ASP.NET Core.

Documentation →

How the protocol works under the hood

Every paid request makes one round-trip to the Lightning Enable hosted API. The middleware never holds key material, never signs macaroons, never verifies preimages locally — all of that is in the hosted backend. The middleware itself is HTTP-client glue.

What you pay for with your Lightning Enable subscription: the protocol broker that lets this be one line of middleware.

Sibling packages

• L402Server — the SDK this middleware is built on. Use directly for non-ASP.NET-Core .NET hosts.
• L402Requests — consumer-side HTTP client. Auto-pays L402 challenges.

Contributing

Open source under MIT. Issues and PRs welcome.

License

MIT © Refined Element