diff --git a/.env.example b/.env.example
index 656d727..90498e7 100644
--- a/.env.example
+++ b/.env.example
@@ -2,6 +2,10 @@
 # testnet | mainnet  (default: testnet)
 STELLAR_NETWORK=testnet
 
+# Frontend network — must match STELLAR_NETWORK; Vite requires the VITE_ prefix
+# to expose env vars to the browser bundle at build time.
+VITE_STELLAR_NETWORK=testnet
+
 # Horizon REST API for the chosen network
 HORIZON_URL=https://horizon-testnet.stellar.org
 
diff --git a/docker-compose.yml b/docker-compose.yml
index 061aa00..6287ed7 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -40,7 +40,10 @@ services:
     restart: unless-stopped
 
   frontend:
-    build: ./frontend
+    build:
+      context: ./frontend
+      args:
+        VITE_STELLAR_NETWORK: ${STELLAR_NETWORK:-testnet}
     # No ports exposed — nginx serves static assets from ./frontend/dist volume
     depends_on:
       backend:
diff --git a/frontend/Dockerfile b/frontend/Dockerfile
index d9fef8e..f6fe884 100644
--- a/frontend/Dockerfile
+++ b/frontend/Dockerfile
@@ -7,6 +7,10 @@ RUN npm install
 
 COPY . .
 
+# Accept network at build time so Vite bakes it into the static bundle
+ARG VITE_STELLAR_NETWORK=testnet
+ENV VITE_STELLAR_NETWORK=$VITE_STELLAR_NETWORK
+
 RUN npm run build
 
 
diff --git a/frontend/src/components/DemoBanner.jsx b/frontend/src/components/DemoBanner.jsx
index 2d674a4..4025289 100644
--- a/frontend/src/components/DemoBanner.jsx
+++ b/frontend/src/components/DemoBanner.jsx
@@ -1,7 +1,25 @@
+import { isTestnet } from '../config/network';
+
 export default function DemoBanner() {
+  if (!isTestnet) return null;
+
   return (
-    <div className="bg-yellow-500 text-slate-900 text-center py-2 px-4 font-bold text-sm sticky top-0 z-50 shadow-md">
-      ⚠️ PUBLIC DEMO ENVIRONMENT — Connected to Stellar Testnet. Records are simulated and database is wiped weekly. Do not enter real medical data.
+    <div
+      role="status"
+      style={{
+        background: '#f59e0b',
+        color: '#1e293b',
+        textAlign: 'center',
+        padding: '0.5rem 1rem',
+        fontWeight: 700,
+        fontSize: '0.85rem',
+        position: 'sticky',
+        top: 0,
+        zIndex: 50,
+        boxShadow: '0 1px 3px rgba(0,0,0,0.12)',
+      }}
+    >
+      TESTNET ENVIRONMENT -- Connected to Stellar Testnet. Records are simulated and the database is wiped weekly. Do not enter real medical data.
     </div>
   );
-}
\ No newline at end of file
+}
diff --git a/frontend/src/components/NavBar.jsx b/frontend/src/components/NavBar.jsx
index eb6035e..e7429e5 100644
--- a/frontend/src/components/NavBar.jsx
+++ b/frontend/src/components/NavBar.jsx
@@ -5,6 +5,7 @@ import Tooltip from './Tooltip';
 import WalletConnectionProgress from './WalletConnectionProgress';
 import { useAuth } from '../hooks/useFreighter';
 import FeedbackButton from './FeedbackButton';
+import NetworkBadge from './NetworkBadge';
 
 const NAV_LINKS = [
   { to: '/', label: 'Home' },
@@ -194,7 +195,10 @@ export default function NavBar({ dark, onToggleDark }) {
 
   return (
     <nav aria-label="Main navigation" style={{ padding: '1rem 2rem', background: 'var(--nav-bg)', display: 'flex', flexWrap: 'wrap', gap: '1.5rem', alignItems: 'center', position: 'relative' }}>
-      <strong style={{ color: 'var(--accent)', fontSize: '1.2rem', flex: 1 }}>💉 VacciChain</strong>
+      <div style={{ display: 'flex', alignItems: 'center', gap: '0.6rem', flex: 1 }}>
+        <strong style={{ color: 'var(--accent)', fontSize: '1.2rem' }}>VacciChain</strong>
+        <NetworkBadge />
+      </div>
 
       {/* Hamburger button — visible only below 640px */}
       <button
diff --git a/frontend/src/components/NetworkBadge.jsx b/frontend/src/components/NetworkBadge.jsx
new file mode 100644
index 0000000..0a91c5d
--- /dev/null
+++ b/frontend/src/components/NetworkBadge.jsx
@@ -0,0 +1,41 @@
+import { STELLAR_NETWORK, isTestnet } from '../config/network';
+
+/**
+ * Small pill badge that shows the active Stellar network (testnet / mainnet).
+ * Testnet is rendered in amber/yellow; mainnet in green.
+ */
+export default function NetworkBadge() {
+  const label = isTestnet ? 'Testnet' : 'Mainnet';
+
+  const badgeStyle = {
+    display: 'inline-flex',
+    alignItems: 'center',
+    gap: '0.35rem',
+    padding: '0.25rem 0.6rem',
+    borderRadius: '9999px',
+    fontSize: '0.7rem',
+    fontWeight: 600,
+    letterSpacing: '0.025em',
+    textTransform: 'uppercase',
+    border: '1px solid',
+    whiteSpace: 'nowrap',
+    ...(isTestnet
+      ? { background: '#fef3c7', color: '#92400e', borderColor: '#fcd34d' }
+      : { background: '#dcfce7', color: '#166534', borderColor: '#86efac' }),
+  };
+
+  const dotStyle = {
+    width: 6,
+    height: 6,
+    borderRadius: '50%',
+    display: 'inline-block',
+    background: isTestnet ? '#f59e0b' : '#22c55e',
+  };
+
+  return (
+    <span style={badgeStyle} aria-label={"Active network: " + label} title={"Stellar " + label}>
+      <span aria-hidden="true" style={dotStyle} />
+      {label}
+    </span>
+  );
+}
diff --git a/frontend/src/config/network.js b/frontend/src/config/network.js
new file mode 100644
index 0000000..b3739b7
--- /dev/null
+++ b/frontend/src/config/network.js
@@ -0,0 +1,20 @@
+/**
+ * Network configuration derived from the VITE_STELLAR_NETWORK environment
+ * variable set at build time.  Defaults to 'testnet' when not specified.
+ *
+ * Usage:
+ *   import { STELLAR_NETWORK, isTestnet } from '../config/network';
+ */
+
+const STELLAR_NETWORK = (import.meta.env.VITE_STELLAR_NETWORK || 'testnet').toLowerCase();
+
+const isTestnet = STELLAR_NETWORK === 'testnet';
+const isMainnet = STELLAR_NETWORK === 'mainnet';
+
+/**
+ * Freighter expects the network name in UPPER CASE ('TESTNET' | 'PUBLIC').
+ * Mainnet is called 'PUBLIC' in the Freighter/Stellar SDK.
+ */
+const freighterNetwork = isMainnet ? 'PUBLIC' : 'TESTNET';
+
+export { STELLAR_NETWORK, isTestnet, isMainnet, freighterNetwork };
diff --git a/frontend/src/hooks/useFreighter.jsx b/frontend/src/hooks/useFreighter.jsx
index 004b0b0..68a653a 100644
--- a/frontend/src/hooks/useFreighter.jsx
+++ b/frontend/src/hooks/useFreighter.jsx
@@ -5,6 +5,7 @@ import {
   signTransaction,
 } from '@stellar/freighter-api';
 import { useToast } from './useToast';
+import { freighterNetwork } from '../config/network';
 
 const AuthContext = createContext(null);
 // Only persist publicKey and role — token is kept in memory only
@@ -40,7 +41,7 @@ export function AuthProvider({ children }) {
     });
     const { transaction, nonce } = await challengeRes.json();
     onStep?.(CONNECTION_STEPS.SIGNING);
-    const signedXDR = await signTransaction(transaction, { network: 'TESTNET' });
+    const signedXDR = await signTransaction(transaction, { network: freighterNetwork });
     onStep?.(CONNECTION_STEPS.VERIFYING);
     const verifyRes = await fetch('/v1/auth/verify', {
       method: 'POST',