diff --git a/extension/app.js b/extension/app.js
index 0043332..a70a6d3 100644
--- a/extension/app.js
+++ b/extension/app.js
@@ -13,14 +13,11 @@ c.browser.runtime.setUninstallURL(
 c.browser.runtime.onMessage.addListener((request, sender, sendResponse) => {
     switch (request.action) {
         case "check": {
-            let crateName = request.crateName;
-            let index = localStorage.getItem(`${crateName}`);
-            sendResponse({added: !!index});
+            sendResponse({added: !!CrateDocSearchManager.checkCrate(request.crateName)});
             break;
         }
         case "remove": {
-            let crateName = request.crateName;
-            let index = localStorage.removeItem(`${crateName}`);
+            CrateDocSearchManager.removeCrate(request.crateName);
             sendResponse(true);
             break;
         }
@@ -29,8 +26,7 @@ c.browser.runtime.onMessage.addListener((request, sender, sendResponse) => {
 });
 
 c.browser.runtime.onMessageExternal.addListener((request, sender, sendResponse) => {
-    let crateName = request.crateName;
-    localStorage.setItem(crateName, JSON.stringify(request.searchIndex[crateName]));
+    CrateDocSearchManager.addCrate(request.crateName, request.crateVersion, request.searchIndex);
     console.log(request);
     sendResponse("ok");
     return true;
diff --git a/extension/script/crate-docs.js b/extension/script/crate-docs.js
index e9522f1..f14c248 100644
--- a/extension/script/crate-docs.js
+++ b/extension/script/crate-docs.js
@@ -1,8 +1,14 @@
-new Compat().browser.runtime.sendMessage("ennpfpdlaclocpomkiablnmbppdnlhoh", {
-        crateName: location.pathname.match(/[0-9a-z_-]+/i)[0],
-        searchIndex: window.searchIndex
-    },
-    (response) => {
-        console.log(response);
-    }
-);
\ No newline at end of file
+(function() {
+    // Parse crate info from location pathname.
+    let [_, crateName, crateVersion, ...others] = location.pathname.split("/");
+
+    new Compat().browser.runtime.sendMessage("ennpfpdlaclocpomkiablnmbppdnlhoh", {
+            crateName,
+            crateVersion,
+            searchIndex: window.searchIndex,
+        },
+        (response) => {
+            console.log(response);
+        }
+    );
+})();
\ No newline at end of file
diff --git a/extension/search/docs/crate-doc.js b/extension/search/docs/crate-doc.js
new file mode 100644
index 0000000..b1ba734
--- /dev/null
+++ b/extension/search/docs/crate-doc.js
@@ -0,0 +1,70 @@
+class CrateDocSearch extends DocSearch {
+    constructor({name, version, searchIndex}) {
+        super(searchIndex, `https://docs.rs/${name}/${version}/`);
+    }
+}
+
+class CrateDocSearchManager {
+    constructor() {
+        this.cachedCrate = null;
+        this.cachedCrateSearcher = null;
+    }
+
+    search(query) {
+        query = query.replace("@", "").trim();
+        let [crateName, keyword] = query.split(" ");
+
+        let searcher = null;
+        if (this.cachedCrate === crateName) {
+            searcher = this.cachedCrateSearcher;
+        } else {
+            let crate = CrateDocSearchManager.getCrate(crateName);
+            if (crate) {
+                searcher = new CrateDocSearch(crate);
+                this.cachedCrate = crate;
+                this.cachedCrateSearcher = searcher;
+                return searcher.search(keyword);
+            } else {
+                return [];
+            }
+        }
+
+        return searcher.search(keyword);
+    }
+
+    static getCrates() {
+        return JSON.parse(localStorage.getItem("crates") || "[]");
+    }
+
+    static checkCrate(name) {
+        let crates = CrateDocSearchManager.getCrates();
+        return crates.find(item => item.name === name);
+    }
+
+    static getCrate(name) {
+        let crate = CrateDocSearchManager.checkCrate(name);
+        if (crate) {
+            crate["searchIndex"] = JSON.parse(localStorage.getItem(`${name}`));
+            return crate;
+        } else {
+            return null;
+        }
+    }
+
+    static addCrate(name, version, searchIndex) {
+        localStorage.setItem(name, JSON.stringify(searchIndex));
+        let crates = CrateDocSearchManager.getCrates();
+        crates.push({name, version});
+        localStorage.setItem("crates", JSON.stringify(crates));
+    }
+
+    static removeCrate(name) {
+        let crates = CrateDocSearchManager.getCrates();
+        let index = crates.findIndex(item => item.name === name);
+        if (index > -1) {
+            crates.splice(index);
+        }
+        localStorage.setItem("crates", JSON.stringify(crates));
+        localStorage.removeItem(`${name}`);
+    }
+}
\ No newline at end of file
diff --git a/manifest.jsonnet b/manifest.jsonnet
index d713d7b..3167d65 100644
--- a/manifest.jsonnet
+++ b/manifest.jsonnet
@@ -36,7 +36,7 @@ local manifest = {
       background: {
         scripts: ["compat.js", "settings.js", "deminifier.js",] +
                  js_files("search" ,["book", "crate", "attribute", "lint"]) +
-                 js_files("search/docs" ,["base", "std",]) +
+                 js_files("search/docs" ,["base", "std", "crate-doc"]) +
                  js_files("index" ,["books", "crates", "std-docs", "lints"]) +
                  js_files("command" ,["base", "history", "manager"]) +
                  ["omnibox.js", "main.js","app.js",]