diff --git a/Program.cs b/Program.cs
index dd6d069..55cb27b 100644
--- a/Program.cs
+++ b/Program.cs
@@ -92,6 +92,13 @@ app.UseMiddleware<ExceptionHandlingMiddleware>();
 app.UseSwagger(options =>
 {
     options.RouteTemplate = "docs/{documentName}/swagger.json";
+    // Advertise the request path base (e.g. /apps/idoklad behind the portal proxy) as the
+    // OpenAPI server so Swagger UI "Try it out" targets {pathBase}/contacts, not the host root.
+    options.PreSerializeFilters.Add((swaggerDoc, httpReq) =>
+    {
+        var basePath = httpReq.PathBase.HasValue ? httpReq.PathBase.Value : "/";
+        swaggerDoc.Servers = new List<OpenApiServer> { new() { Url = basePath } };
+    });
 });
 app.UseSwaggerUI(options =>
 {