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diff --git a/index.html b/index.html
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--- a/index.html
+++ b/index.html
@@ -5,6 +5,25 @@
     <link rel="icon" type="image/svg+xml" href="./src/assets/favicon.svg" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>NetGraph</title>
+
+    <!-- Social / link-unfurl metadata. og:image is served from GitHub raw, so it
+         resolves without any asset hosting on the deployed site. -->
+    <meta name="description" content="Map your home or lab network in the browser. Devices and connections are stored entirely in localStorage - no backend, no accounts, no telemetry." />
+    <meta property="og:type" content="website" />
+    <meta property="og:site_name" content="NetGraph" />
+    <meta property="og:title" content="NetGraph - local network visualizer" />
+    <meta property="og:description" content="Map your home or lab network in the browser. Devices and connections are stored entirely in localStorage - no backend, no accounts, no telemetry." />
+    <meta property="og:url" content="https://netgraph.khemul.de/" />
+    <meta property="og:image" content="https://raw.githubusercontent.com/BrainInBlack/NetGraph/main/docs/social-preview.png" />
+    <meta property="og:image:type" content="image/png" />
+    <meta property="og:image:width" content="1280" />
+    <meta property="og:image:height" content="640" />
+    <meta property="og:image:alt" content="NetGraph - a local network visualizer, showing the wordmark and a sample device topology." />
+    <meta name="twitter:card" content="summary_large_image" />
+    <meta name="twitter:title" content="NetGraph - local network visualizer" />
+    <meta name="twitter:description" content="Map your home or lab network in the browser. Devices and connections are stored entirely in localStorage - no backend, no accounts, no telemetry." />
+    <meta name="twitter:image" content="https://raw.githubusercontent.com/BrainInBlack/NetGraph/main/docs/social-preview.png" />
+    <meta name="twitter:image:alt" content="NetGraph - a local network visualizer, showing the wordmark and a sample device topology." />
   </head>
   <body>
     <div id="app">
