diff --git a/bun.lockb b/bun.lockb
index 4eb5e31..8645e16 100755
Binary files a/bun.lockb and b/bun.lockb differ
diff --git a/index.ts b/index.ts
index 9f900ec..f8ddb2a 100644
--- a/index.ts
+++ b/index.ts
@@ -1,36 +1,132 @@
-Bun.serve({
-    port: 41691,
-    async fetch(req: Request) {
-        if (req.method == "OPTIONS") {
-            return new Response(null)
-        }
-        const url = new URL(req.url, "https://loc.al/");
+const { App, ExpressReceiver } = (await import("@slack/bolt"));
+import postgres from "postgres";
+import "dotenv/config";
+import bcrypt from "bcrypt";
 
-        if (url.pathname == "/callback") {
-            const code = url.searchParams.get("code");
+const sql = postgres({
+    host: '/var/run/postgresql',
+    database: 'haroon_osu',
+    username: 'haroon'
+})
 
-            const data = await fetch("https://osu.ppy.sh/oauth/token", {
-                method: "POST",
-                headers: {
-                    "Content-Type": "application/x-www-form-urlencoded"
-                },
-                body: `client_id=33126&client_secret=${encodeURIComponent(Bun.env.CLIENT_SECRET!)}&code=${code}&grant_type=authorization_code&redirect_uri=${encodeURIComponent("https://osu.haroon.hackclub.app/callback")}`
-            }).then(res => res.json());
+const receiver = new ExpressReceiver({ signingSecret: process.env.SLACK_SIGNING_SECRET! })
 
-            if (data.error) {
-                console.log(data)
-                return new Response(`Something went wrong: \n\n${data.message} (${data.error})\n\nThis has been reported.`)
-            } else {
-                const user = await fetch("https://osu.ppy.sh/api/v2/me", {
-                    headers: {
-                        "Authorization": `Bearer ${data.access_token}`
-                    }
-                }).then(res => res.json());
-
-                return new Response(`Hello, ${user.username}!`)
-            }
-        }
-
-        return new Response(null, { status: 404 });
+const app = new App({
+    token: process.env.SLACK_BOT_TOKEN,
+    signingSecret: process.env.SLACK_SIGNING_SECRET,
+    receiver,
+    installerOptions: {
+        port: 41691
     }
-})
\ No newline at end of file
+});
+
+const states = new Map();
+
+app.command("/osu-link", async (ctx) => {
+    await ctx.ack();
+
+    const [ exists = null ] = await sql`SELECT osu_id FROM links WHERE slack_id = ${ctx.context.userId}`;
+
+    if (exists) {
+        return ctx.respond({
+            text: "This slack account is already linked to an osu! account.",
+            unfurl_links: true,
+            blocks: [
+                {
+                    type: 'section',
+                    text: {
+                        type: "mrkdwn",
+                        text: `This slack account is already linked to an <https://osu.ppy.sh/users/${exists.osu_id}/|osu! account>.`
+                    }
+                }
+            ]            
+
+        })
+
+        return;
+    }
+
+    const verifCode = `OSULEADERBOARD-${ctx.context.userId}-${Date.now()}`;
+
+    states.set(ctx.context.userId, verifCode);
+
+    const encodedCode = await bcrypt.hash(verifCode, 10);
+
+    ctx.respond({
+        replace_original: true,
+        text: "View this message in your client to verify!",
+        blocks: [
+            {
+                type: 'section',
+                text: {
+                    type: "mrkdwn",
+                    text: `Hey <@${ctx.context.userId}>! To link your osu! account to your Slack account, click this button:`
+                },
+                "accessory": {
+                    "type": "button",
+                    "text": {
+                        "type": "plain_text",
+                        "text": "Link account",
+                        "emoji": true
+                    },
+                    "value": "link",
+                    "url": `https://osu.ppy.sh/oauth/authorize?client_id=33126&redirect_uri=https://osu.haroon.hackclub.app/osu/callback&response_type=code&state=${encodeURIComponent(ctx.context.userId + ":" + encodedCode)}`,
+                    "action_id": "link"
+                }
+            }
+        ]
+    })
+})
+
+receiver.router.get("/osu/callback", async (req, res) => {
+    res.contentType("text/html")
+
+    const code = req.query.code as string;
+    const state = req.query.state as string;
+
+    const [userId, hash] = state.split(':');
+
+    try {
+        const isValid = await bcrypt.compare(states.get(userId), hash);
+
+        if (!isValid) {
+            throw new Error();
+        }
+    } catch (err) {
+        return res.send(`Something went wrong: <br><br>Your state was invalid. Please re-authenticate. (invalid_state)<br><br>This has been reported.`)
+    }
+
+    states.delete(userId);
+
+    const data = await fetch("https://osu.ppy.sh/oauth/token", {
+        method: "POST",
+        headers: {
+            "Content-Type": "application/x-www-form-urlencoded"
+        },
+        body: `client_id=33126&client_secret=${encodeURIComponent(process.env.CLIENT_SECRET!)}&code=${code}&grant_type=authorization_code&redirect_uri=${encodeURIComponent("https://osu.haroon.hackclub.app/osu/callback")}`
+    }).then(res => res.json());
+
+    if (data.error) {
+        console.log(data)
+        return res.send(`Something went wrong: <br><br>${data.message} (${data.error})<br><br>This has been reported.`)
+    } else {
+        const user = await fetch("https://osu.ppy.sh/api/v2/me", {
+            headers: {
+                "Authorization": `Bearer ${data.access_token}`
+            }
+        }).then(res => res.json());
+
+        // {user.id} - osu! user ID
+        // userId - slack user ID
+
+        sql`INSERT INTO links VALUES (${user.id}, ${userId})`
+
+        return res.send(`Your osu! account (${user.id}) has been successfully linked to your Slack account (${userId})!`)
+    }
+})
+
+;(async () => {
+    await app.start(41691);
+
+    console.log('⚡️ Bolt app is running!');
+})();
\ No newline at end of file
diff --git a/package.json b/package.json
index d092803..b37c796 100644
--- a/package.json
+++ b/package.json
@@ -7,5 +7,12 @@
   },
   "peerDependencies": {
     "typescript": "^5.0.0"
+  },
+  "dependencies": {
+    "@slack/bolt": "^3.19.0",
+    "@types/bcrypt": "^5.0.2",
+    "bcrypt": "^5.1.1",
+    "dotenv": "^16.4.5",
+    "postgres": "^3.4.4"
   }
 }
\ No newline at end of file