diff --git a/browser-extension/README.md b/browser-extension/README.md
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+# OTOMADB Browser Extension
+
+## Disclaimer
+
+Code is heavily inspired from lachrymaLF/otodb.
diff --git a/browser-extension/icons/512.png b/browser-extension/icons/512.png
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diff --git a/browser-extension/main.js b/browser-extension/main.js
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+async function injectContainer(inject) {
+  const $container = document.createElement('div');
+  $container.id = 'otomadb-container';
+
+  const $containerTitle = document.createElement('p');
+  $containerTitle.innerText = "OTOMADB Data";
+  $containerTitle.setAttribute("class", "otomadb-title");
+  $container.appendChild($containerTitle);
+
+  const $status = document.createElement('p');
+  $status.innerText = "Fetching...";
+  $container.appendChild($status);
+
+  inject($container);
+
+  const apiUrl = new URL("/api/extension", "http:localhost:5173");
+  apiUrl.searchParams.set("url", window.location.toString());
+
+  const res = await fetch(apiUrl.toString(), { mode: 'cors' });
+  if (!res.ok) {
+    $status.innerText = "Not found";
+    inject($container);
+    return;
+  }
+
+  const data = await res.json();
+  $status.remove();
+
+  console.dir(data.status);
+
+  switch (data.status) {
+    case "source_not_registered": {
+      console.log("Source not registered");
+    } break;
+    case "otomad_not_registered": {
+      console.log("Source registed, but otomad not registered");
+    } break;
+    case "ok": {
+      console.log("Otomad registed")
+      const { otomad, originalSource } = data.data;
+
+      const $title = document.createElement('p');
+      $title.setAttribute("class", "otomadb-otomad-title");
+      const $titleLink = document.createElement('a');
+      $titleLink.innerText = otomad.title;
+      $titleLink.setAttribute("href", new URL("/otomad/" + otomad.serial, "http://localhost:5173").toString());
+      // $titleLink.setAttribute("target", "_blank");
+      // $titleLink.setAttribute("rel", "noopener noreferrer");
+      $titleLink.setAttribute("lang", otomad.titleLang);
+      $title.appendChild($titleLink);
+      $container.appendChild($title);
+
+
+      const $taggings = document.createElement('div');
+      $taggings.setAttribute("class", "otomadb-otomad-taggings");
+      for (const { tag } of otomad.taggings) {
+        const $tagging = document.createElement("a");
+        $tagging.innerText = tag.name
+        $tagging.setAttribute("class", "otomadb-otomad-tagging");
+        $tagging.setAttribute("href", new URL("/tags/" + tag.serial, "http://localhost:5173").toString());
+        // $tagging.setAttribute("target", "_blank");
+        // $tagging.setAttribute("rel", "noopener noreferrer");
+        $tagging.setAttribute("lang", tag.nameLang);
+        $taggings.appendChild($tagging);
+      }
+      $container.appendChild($taggings);
+
+      const $sources = document.createElement('div');
+      $sources.setAttribute("class", "otomadb-otomad-sources");
+      for (const source of otomad.sources) {
+        const $source = document.createElement('a');
+        $source.innerText = `${source.platform}`;
+        $source.setAttribute("class", "otomadb-otomad-source");
+        $source.setAttribute("href", new URL(source.url));
+        // $source.setAttribute("target", "_blank");
+        // $source.setAttribute("rel", "noopener noreferrer");
+        $sources.appendChild($source);
+      }
+      $container.appendChild($sources);
+    } break;
+  }
+
+}
+
+function waitForTarget(get_target, mutation_props, mutation_host = document) {
+  return new Promise(resolve => {
+    let t = get_target([]);
+    if (t) return resolve(t);
+
+    const observer = new MutationObserver((records, observer) => {
+      let target = get_target(records);
+      if (target) {
+        resolve(target);
+        observer.disconnect();
+      }
+    });
+    observer.observe(mutation_host, mutation_props);
+  });
+}
+
+async function init() {
+  console.log("Init");
+
+  switch (window.location.hostname) {
+    case "www.nicovideo.jp": {
+      const $target = await waitForTarget(records => document.getElementsByClassName('grid-area_[meta]')[0]?.firstElementChild, { subtree: true, childList: true });
+      await injectContainer(
+        $container => $target.insertAdjacentElement('afterend', $container),
+      );
+    }
+      break;
+    case "www.bilibili.com": {
+      await injectContainer(
+        $container => document.querySelector('.video-desc-container').insertAdjacentElement('afterend', $container),
+      );
+    }
+      break;
+    case "www.youtube.com": {
+      const $target = await waitForTarget(records => document.querySelector('#bottom-row'), { subtree: true, childList: true });
+      await injectContainer(
+        $container => $target.insertAdjacentElement('afterend', $container),
+      );
+    }
+      break;
+  }
+}
+
+if (document.readyState === 'loading') {
+  document.addEventListener('DOMContentLoaded', init);
+} else {
+  init()
+}
diff --git a/browser-extension/manifest.json b/browser-extension/manifest.json
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+++ b/browser-extension/manifest.json
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+{
+  "manifest_version": 3,
+  "name": "OTOMADB Browser Extension",
+  "version": "1.0",
+  "description": "-",
+  "icons": {
+    "512": "icons/512.png"
+  },
+  "content_scripts": [
+    {
+      "matches": [
+        "*://*.bilibili.com/video*",
+        "*://*.nicovideo.jp/watch*",
+        "*://*.youtube.com/watch*"
+      ],
+      "js": [
+        "main.js"
+      ],
+      "css": [
+        "style.css"
+      ]
+    }
+  ],
+  "host_permissions": [
+    "*://localhost/*"
+  ]
+}
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diff --git a/browser-extension/style.css b/browser-extension/style.css
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+#otomadb-container {
+  padding: 12px 16px;
+  margin: 8px 0;
+  background: #252525;
+  border-radius: 8px;
+}
+
+#otomadb-container .otomadb-title {
+  font-family: sans-serif;
+  font-size: 12px;
+  color: white;
+  margin-bottom: 8px;
+}
+
+#otomadb-container .otomadb-otomad-title {
+  font-family: sans-serif;
+  color: white;
+  margin-bottom: 8px;
+}
+
+#otomadb-container .otomadb-otomad-title>a {
+  color: white;
+  font-size: 24px;
+  font-weight: bold;
+  text-decoration: none;
+}
+
+#otomadb-container .otomadb-otomad-taggings {
+  display: flex;
+  flex-wrap: wrap;
+  column-gap: 4px;
+}
+
+#otomadb-container .otomadb-otomad-tagging {
+  display: block;
+  font-family: sans-serif;
+  font-size: 14px;
+  padding: 2px 8px;
+  color: #2f2f2f;
+  border: 1px solid #2f2f2f;
+  border-radius: 4px;
+  background-color: #f0f0f0;
+  text-decoration: none;
+}
+
+#otomadb-container .otomadb-otomad-tagging:hover {
+  background: #c2c2c2;
+}
+
+
+#otomadb-container .otomadb-otomad-sources {
+  display: flex;
+  flex-wrap: wrap;
+  column-gap: 8px;
+  margin-top: 16px;
+}
+
+#otomadb-container .otomadb-otomad-source {
+  display: block;
+  font-family: sans-serif;
+  color: white;
+  font-size: 12px;
+  text-decoration: none;
+}
+
+#otomadb-container .otomadb-otomad-source:hover {
+  text-decoration: underline;
+}
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