diff --git a/Dockerfile b/Dockerfile
index a8c0698..c92f126 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -14,8 +14,8 @@ COPY Cargo.lock Cargo.toml index.html ./
 COPY src ./src
 COPY style ./style
 
-# Build for release.
-RUN trunk build --release
+# Build for preview release.
+RUN NC_BETA_BUILD="" trunk build --release
 
 FROM nginx:latest
 
diff --git a/src/main.rs b/src/main.rs
index 3e5378f..deb0912 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,6 +5,7 @@ mod topbar;
 use anyhow::Result;
 use backend::Session;
 use content::{about::About, error, home::Home};
+use gloo::dialogs::alert;
 use std::ops::Deref;
 use topbar::TopBar;
 use yew::prelude::*;
@@ -47,13 +48,11 @@ fn App() -> Html {
 
     let cloned_state = state.clone();
     let callbacks = use_state(move || Callbacks {
-        sign_in: Callback::from(
-            move |token: String| {
-                let mut new_state = cloned_state.deref().clone();
-                new_state.set_token(token);
-                cloned_state.set(new_state);
-            },
-        ),
+        sign_in: Callback::from(move |token: String| {
+            let mut new_state = cloned_state.deref().clone();
+            new_state.set_token(token);
+            cloned_state.set(new_state);
+        }),
     });
 
     html! {
@@ -71,5 +70,8 @@ fn App() -> Html {
 }
 
 fn main() {
+    if option_env!("NC_BETA_BUILD").is_some() {
+        alert("This is a beta preview!\nThe UI and the backend are subjects to change. Data persistence can't be guaranteed.");
+    }
     yew::Renderer::<App>::new().render();
 }