CAD & architecture extensions
License key system for Revit add-ins, SketchUp extensions, and Rhino/Grasshopper plugins
There is no standard way to sell and license third-party Revit add-ins, SketchUp extensions, or Grasshopper plugins. Licensr gives AEC developers a turnkey license key system with machine-locked activation, Stripe payments, and a branded storefront — one REST API that works across every BIM and CAD platform.
Step-by-step integration guide// Revit 2025+ (.NET 8), in ExternalApplication.OnStartup
// First run: call /v1/license/activate once (see the guide)
public Result OnStartup(UIControlledApplication app)
{
using var http = new HttpClient();
var body = JsonSerializer.Serialize(new
{
license_key = Settings.LicenseKey,
plugin_slug = "my-revit-addon",
});
var req = new HttpRequestMessage(HttpMethod.Post,
"https://api.licensr.app/v1/license/validate")
{
Content = new StringContent(
body, Encoding.UTF8, "application/json"),
};
req.Headers.Authorization =
new AuthenticationHeaderValue("Bearer", API_KEY);
try
{
var res = http.Send(req);
using var doc = JsonDocument.Parse(
res.Content.ReadAsStream());
if (doc.RootElement.TryGetProperty("valid", out var v)
&& v.ValueKind == JsonValueKind.False)
{
TaskDialog.Show("License",
"Invalid or expired license.");
return Result.Failed;
}
}
catch (Exception) { } // no answer: keep the previous state
return Result.Succeeded;
}Compatible CAD, BIM & AEC platforms
Why AEC developers choose Licensr for plugin licensing
No standard license key system in AEC software
Revit, SketchUp, Rhino, ArchiCAD, and Vectorworks offer no built-in licensing for third-party developers. Licensr fills that gap with a complete license key system — validation, activation, Stripe payments, and a customer portal included.
Machine-locked license keys prevent firm-wide sharing
AEC add-ins and BIM tools often carry premium prices. Machine-locked activations prevent a single license key from being shared across an entire architecture firm without paying for additional seats.
Sell direct — no Autodesk App Store or marketplace fees
Your Revit add-in or SketchUp extension gets its own buy page. Architects and engineers pay via Stripe on your own account. No Autodesk App Store cut, no middleman.
One API for Revit, SketchUp, Rhino, ArchiCAD, and more
Whether your extension is written in C# for Revit, Ruby for SketchUp, Python for Rhino/Grasshopper, or C++ for ArchiCAD — the same REST call validates the license key. Use the official C# SDK in .NET 8 hosts (Revit 2025+, Rhino 8); older hosts and other languages call the API directly.
Annual subscription billing handled automatically
Sell annual or monthly subscriptions that auto-renew via Stripe. When a subscription lapses, the validate call returns false — no manual revocation, no chasing expired licenses.
Official SDK
Official C# SDK: Revit, Rhino, and .NET CAD hosts
Licensr.Sdk targets netstandard2.1 and net8.0, so it drops into Revit/AutoCAD 2025+ and Rhino 8 plugins. Older .NET Framework 4.8 hosts (Revit/AutoCAD 2024 and earlier, Rhino 7), SketchUp (Ruby), and ArchiCAD (C++) call the same REST API directly.
using Licensr.Sdk;
var client = new LicensrClient(new() {
ApiKey = "pk_live_...",
PluginSlug = "my-synth",
});
var result = await client.ValidateAsync(new() {
LicenseKey = userKey,
});
if (result.Valid) UnlockFullFeatures();
// → Valid = true, Entitlement = Full,
// FeatureFlags = { "auto_backup": true }Ready to license and sell your CAD extension?
Free tier available. From signup to a working license key validation in about 30 minutes.