diff --git a/src/mobx/stores/Auth.ts b/src/mobx/stores/Auth.ts
index 1a4d8d09..9d61d956 100644
--- a/src/mobx/stores/Auth.ts
+++ b/src/mobx/stores/Auth.ts
@@ -1,4 +1,4 @@
-import { makeAutoObservable } from "mobx";
+import { makeAutoObservable, ObservableMap } from "mobx";
 import { Session } from "revolt-api/types/Auth";
 import { Nullable } from "revolt.js/dist/util/null";
 
@@ -15,14 +15,14 @@ interface Data {
  * accounts and their sessions.
  */
 export default class Auth implements Persistent<Data> {
-    private sessions: Record<string, Session>;
+    private sessions: ObservableMap<string, Session>;
     private current: Nullable<string>;
 
     /**
      * Construct new Auth store.
      */
     constructor() {
-        this.sessions = {};
+        this.sessions = new ObservableMap();
         this.current = null;
         makeAutoObservable(this);
     }
@@ -37,8 +37,11 @@ export default class Auth implements Persistent<Data> {
 
     // eslint-disable-next-line require-jsdoc
     hydrate(data: Data) {
-        this.sessions = data.sessions;
-        if (data.current && this.sessions[data.current]) {
+        Object.keys(data.sessions).forEach((id) =>
+            this.sessions.set(id, data.sessions[id]),
+        );
+
+        if (data.current && this.sessions.has(data.current)) {
             this.current = data.current;
         }
     }
@@ -48,11 +51,7 @@ export default class Auth implements Persistent<Data> {
      * @param session Session
      */
     setSession(session: Session) {
-        this.sessions = {
-            ...this.sessions,
-            [session.user_id]: session,
-        };
-
+        this.sessions.set(session.user_id, session);
         this.current = session.user_id;
     }
 
diff --git a/src/mobx/stores/Experiments.ts b/src/mobx/stores/Experiments.ts
new file mode 100644
index 00000000..bb0a35dc
--- /dev/null
+++ b/src/mobx/stores/Experiments.ts
@@ -0,0 +1,86 @@
+import { action, computed, makeAutoObservable, ObservableSet } from "mobx";
+
+import Persistent from "../Persistent";
+
+export type Experiment = "search" | "theme_shop";
+
+export const AVAILABLE_EXPERIMENTS: Experiment[] = ["theme_shop"];
+
+export const EXPERIMENTS: {
+    [key in Experiment]: { title: string; description: string };
+} = {
+    search: {
+        title: "Search",
+        description: "Allows you to search for messages in channels.",
+    },
+    theme_shop: {
+        title: "Theme Shop",
+        description: "Allows you to access and set user submitted themes.",
+    },
+};
+
+interface Data {
+    enabled?: Experiment[];
+}
+
+/**
+ * Handles enabling and disabling client experiments.
+ */
+export default class Experiments implements Persistent<Data> {
+    private enabled: ObservableSet<Experiment>;
+
+    /**
+     * Construct new Experiments store.
+     */
+    constructor() {
+        this.enabled = new ObservableSet();
+        makeAutoObservable(this);
+    }
+
+    // eslint-disable-next-line require-jsdoc
+    toJSON() {
+        return {
+            enabled: this.enabled,
+        };
+    }
+
+    // eslint-disable-next-line require-jsdoc
+    @action hydrate(data: Data) {
+        if (data.enabled) {
+            for (const experiment of data.enabled) {
+                this.enabled.add(experiment as Experiment);
+            }
+        }
+    }
+
+    /**
+     * Check if an experiment is enabled.
+     * @param experiment Experiment
+     */
+    @computed isEnabled(experiment: Experiment) {
+        return this.enabled.has(experiment);
+    }
+
+    /**
+     * Enable an experiment.
+     * @param experiment Experiment
+     */
+    @action enable(experiment: Experiment) {
+        this.enabled.add(experiment);
+    }
+
+    /**
+     * Disable an experiment.
+     * @param experiment Experiment
+     */
+    @action disable(experiment: Experiment) {
+        this.enabled.delete(experiment);
+    }
+
+    /**
+     * Reset and disable all experiments.
+     */
+    @action reset() {
+        this.enabled.clear();
+    }
+}
diff --git a/src/mobx/stores/LastOpened.ts b/src/mobx/stores/LastOpened.ts
new file mode 100644
index 00000000..091bc012
--- /dev/null
+++ b/src/mobx/stores/LastOpened.ts
@@ -0,0 +1,57 @@
+import { action, computed, makeAutoObservable, ObservableMap } from "mobx";
+
+import Persistent from "../Persistent";
+
+interface Data {
+    server?: Record<string, string>;
+}
+
+/**
+ * Keeps track of the last open channels, tabs, etc.
+ * Handles providing good UX experience on navigating
+ * back and forth between different parts of the app.
+ */
+export default class Experiments implements Persistent<Data> {
+    private server: ObservableMap<string, string>;
+
+    /**
+     * Construct new Experiments store.
+     */
+    constructor() {
+        this.server = new ObservableMap();
+        makeAutoObservable(this);
+    }
+
+    // eslint-disable-next-line require-jsdoc
+    toJSON() {
+        return {
+            server: this.server,
+        };
+    }
+
+    // eslint-disable-next-line require-jsdoc
+    @action hydrate(data: Data) {
+        if (data.server) {
+            Object.keys(data.server).forEach((key) =>
+                this.server.set(key, data.server![key]),
+            );
+        }
+    }
+
+    /**
+     * Get last opened channel in a server.
+     * @param server Server ID
+     */
+    @computed get(server: string) {
+        return this.server.get(server);
+    }
+
+    /**
+     * Set last opened channel in a server.
+     * @param server Server ID
+     * @param channel Channel ID
+     */
+    @action enable(server: string, channel: string) {
+        this.server.set(server, channel);
+    }
+}
diff --git a/src/mobx/stores/LocaleOptions.ts b/src/mobx/stores/LocaleOptions.ts
new file mode 100644
index 00000000..6f88d2f7
--- /dev/null
+++ b/src/mobx/stores/LocaleOptions.ts
@@ -0,0 +1,84 @@
+import { action, computed, makeAutoObservable } from "mobx";
+
+import { Language, Languages } from "../../context/Locale";
+
+import Persistent from "../Persistent";
+
+interface Data {
+    lang: Language;
+}
+
+/**
+ * Detect the browser language or match given language.
+ * @param lang Language to find
+ * @returns Matched Language
+ */
+export function findLanguage(lang?: string): Language {
+    if (!lang) {
+        if (typeof navigator === "undefined") {
+            lang = Language.ENGLISH;
+        } else {
+            lang = navigator.language;
+        }
+    }
+
+    const code = lang.replace("-", "_");
+    const short = code.split("_")[0];
+
+    const values = [];
+    for (const key in Language) {
+        const value = Language[key as keyof typeof Language];
+
+        // Skip alternative/joke languages
+        if (Languages[value].cat === "alt") continue;
+
+        values.push(value);
+        if (value.startsWith(code)) {
+            return value as Language;
+        }
+    }
+
+    for (const value of values.reverse()) {
+        if (value.startsWith(short)) {
+            return value as Language;
+        }
+    }
+
+    return Language.ENGLISH;
+}
+
+/**
+ * Keeps track of the last open channels, tabs, etc.
+ * Handles providing good UX experience on navigating
+ * back and forth between different parts of the app.
+ */
+export default class LocaleOptions implements Persistent<Data> {
+    private lang: Language;
+
+    /**
+     * Construct new LocaleOptions store.
+     */
+    constructor() {
+        this.lang = findLanguage();
+        makeAutoObservable(this);
+    }
+
+    // eslint-disable-next-line require-jsdoc
+    toJSON() {
+        return {
+            lang: this.lang,
+        };
+    }
+
+    // eslint-disable-next-line require-jsdoc
+    @action hydrate(data: Data) {
+        this.lang = data.lang;
+    }
+
+    /**
+     * Get current language.
+     */
+    @computed getLang() {
+        return this.lang;
+    }
+}