diff --git a/README.md b/README.md
index 970ca779..3dc1fedc 100644
--- a/README.md
+++ b/README.md
@@ -45,6 +45,8 @@ docker compose logs -f api             # wait for "Application started"
 
 SQL Server needs about 2 GB of RAM. Use a plan with at least 4 GB in total.
 
+Security defaults: the API refuses to start outside Development without `JWT_SECRET`; browsers may call the API only from `https://SITE_DOMAIN` (`Cors:AllowedOrigins`); public sign-up is off (`SIGNUP_ENABLED=False`) until SMTP (`SmptConfig__*`) is configured.
+
 ### Load the data
 
 1. Open `https://SITE_DOMAIN/login` and sign in with `ADMIN_EMAIL` and the password **`Test!123`**. The first login creates the admin account with that fixed password (RSecurityBackend's default; upstream's guide is wrong about this). **Change it right away** in the user panel.
diff --git a/RMuseum/Startup.cs b/RMuseum/Startup.cs
index f37102de..78e3f559 100644
--- a/RMuseum/Startup.cs
+++ b/RMuseum/Startup.cs
@@ -34,6 +34,7 @@ using RSecurityBackend.Services.Implementation;
 using RSecurityBackend.Utilities;
 using Swashbuckle.AspNetCore.Filters;
 using System;
+using System.Linq;
 using System.IO;
 using System.Reflection;
 using System.Text;
@@ -51,6 +52,10 @@ namespace RMuseum
 
         public IConfiguration Configuration { get; }
 
+        private string[] AllowedOrigins => (Configuration["Cors:AllowedOrigins"] ?? "")
+            .Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
+            .Select(o => o.TrimEnd('/')).ToArray();
+
         // This method gets called by the runtime. Use this method to add services to the container.
         public void ConfigureServices(IServiceCollection services)
         {
@@ -58,7 +63,9 @@ namespace RMuseum
             services.AddCors(options =>
             {
                 options.AddPolicy("DiwanCorsPolicy",
-                    builder => builder.SetIsOriginAllowed(_ => true)
+                    // diwan: Cors:AllowedOrigins (comma separated, e.g. https://diwan.example) restricts browsers;
+                    // unset = any origin (local development)
+                    builder => builder.SetIsOriginAllowed(origin => AllowedOrigins.Length == 0 || AllowedOrigins.Contains(origin.TrimEnd('/'), StringComparer.OrdinalIgnoreCase))
                     .AllowAnyMethod()
                     .AllowAnyHeader()
                     .WithExposedHeaders("paging-headers", "audio-upload-enabled", "items-count")
@@ -353,6 +360,9 @@ namespace RMuseum
         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
         public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
         {
+            // diwan: never run outside Development with a missing JWT signing secret (upstream shipped a public default)
+            if (!env.IsDevelopment() && string.IsNullOrWhiteSpace(Configuration["Security:Secret"]))
+                throw new InvalidOperationException("Security:Secret is not set (env Security__Secret). Refusing to start.");
             if (env.IsDevelopment())
             {
                 app.UseDeveloperExceptionPage();
diff --git a/RMuseum/appsettings.json b/RMuseum/appsettings.json
index aeb8ae42..14487706 100644
--- a/RMuseum/appsettings.json
+++ b/RMuseum/appsettings.json
@@ -4,7 +4,7 @@
   },
   "RSecurityBackend": {
     "ApplicationName": "Diwan",
-    "FirstUserEmail": "admin@ganjoor.net"
+    "FirstUserEmail": "admin@diwan.local"
   },
   "BackgroundTaskQueue": {
     "MaxConcurrency": "1"
@@ -27,7 +27,7 @@
     }
   },
   "Security": {
-    "Secret": "k4Fy7pDsc0LgXQ8PCCfZtwmju5Ed8asc",
+    "Secret": "",
     "DefaultTokenExpirationInSeconds": "3600",
     "SessionIdleTimeoutInDays": "90"
   },
@@ -57,8 +57,8 @@
     "ShowAccountInfo": "False"
   },
   "Diwan": {
-    "SystemEmail": "sys@ganjoor.net",
-    "DeleteUserEmail": "del@ganjoor.net",
+    "SystemEmail": "sys@diwan.local",
+    "DeleteUserEmail": "del@diwan.local",
     "SitemapLocation": "C:\\inetpub\\diwan\\wwwroot\\sitemap.xml",
     "GDBStorage": "D:\\My Documents\\My Web Design\\diwan\\www\\i\\android\\sgdb",
     "GDBStorageImageSource": "D:\\My Documents\\My Web Design\\diwan\\www\\i\\android\\img",
@@ -75,7 +75,7 @@
     "RemoteUrl": "https://github.com/ganjoor/ganjoor-data.git",
     "Branch": "main",
     "CommitAuthorName": "Diwan Export Bot",
-    "CommitAuthorEmail": "bot@ganjoor.net",
+    "CommitAuthorEmail": "bot@diwan.local",
     "PushEnabled": "False",
     "GitUserName": "",
     "GitToken": "",
diff --git a/docker-compose.yml b/docker-compose.yml
index 5f2babf5..fb449c71 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -25,6 +25,7 @@ services:
       RSecurityBackend__ApplicationName: Diwan
       RSecurityBackend__FirstUserEmail: ${ADMIN_EMAIL:?set in .env}
       SignUp__Enabled: ${SIGNUP_ENABLED:-False}
+      Cors__AllowedOrigins: https://${SITE_DOMAIN}       # only the site may call the API from browsers
       WebServiceUrl: https://${API_DOMAIN}
       # Linux paths for upstream's Windows defaults
       PictureFileService__StoragePath: /data/museum