diff --git a/apps/web/src/app/(ui)/(public)/auth/hackclub/callback/route.ts b/apps/web/src/app/(ui)/(public)/auth/hackclub/callback/route.ts
index dd3f44b..aae72ef 100644
--- a/apps/web/src/app/(ui)/(public)/auth/hackclub/callback/route.ts
+++ b/apps/web/src/app/(ui)/(public)/auth/hackclub/callback/route.ts
@@ -1,3 +1,4 @@
+import slackNotifier from '@/lib/services/slackNotifier';
 import { hackClub, lucia, HCID_TOKEN_URL, HCID_USER_INFO_URL } from '@hctv/auth';
 import { cookies as nextCookies } from 'next/headers';
 import { OAuth2RequestError } from 'arctic';
@@ -49,6 +50,13 @@ export async function GET(request: Request): Promise<Response> {
       });
     }
 
+    const slackValidation = await validateSlackUser(slackId);
+    if (!slackValidation.success) {
+      return new Response(slackValidation.message, {
+        status: slackValidation.status,
+      });
+    }
+
     const existingUser = await prisma.user.findFirst({
       where: {
         slack_id: slackId,
@@ -130,6 +138,16 @@ interface HackClubUserResponse {
 
 type VerificationStatus = 'needs_submission' | 'pending' | 'verified' | 'ineligible';
 
+type SlackValidationResult =
+  | {
+      success: true;
+    }
+  | {
+      success: false;
+      message: string;
+      status: number;
+    };
+
 function getVerificationErrorMessage(status: VerificationStatus): string {
   switch (status) {
     case 'needs_submission':
@@ -142,3 +160,49 @@ function getVerificationErrorMessage(status: VerificationStatus): string {
       return 'Verified users can continue.';
   }
 }
+
+async function validateSlackUser(slackId: string): Promise<SlackValidationResult> {
+  if (!process.env.SLACK_NOTIFIER_TOKEN) {
+    return {
+      success: false,
+      message: 'Slack verification is not configured right now. Please try again later.',
+      status: 503,
+    };
+  }
+
+  try {
+    const response = await slackNotifier.users.info({ user: slackId });
+    if (!response.ok || !response.user) {
+      return {
+        success: false,
+        message: 'Unable to verify your Slack account right now. Please try again later.',
+        status: 502,
+      };
+    }
+
+    if (response.user.deleted) {
+      return {
+        success: false,
+        message: 'Your Slack account is deactivated, so you cannot access hackclub.tv.',
+        status: 403,
+      };
+    }
+
+    if (response.user.is_restricted || response.user.is_ultra_restricted) {
+      return {
+        success: false,
+        message:
+          'Guest Slack accounts cannot access hackclub.tv. Please sign in with a full Hack Club Slack account.',
+        status: 403,
+      };
+    }
+
+    return { success: true };
+  } catch {
+    return {
+      success: false,
+      message: 'Unable to verify your Slack account right now. Please try again later.',
+      status: 502,
+    };
+  }
+}
diff --git a/packages/auth/src/index.ts b/packages/auth/src/index.ts
index 0e722b5..53b4214 100644
--- a/packages/auth/src/index.ts
+++ b/packages/auth/src/index.ts
@@ -10,9 +10,9 @@ export const hackClub = new OAuth2Client(
   process.env.HCID_REDIRECT_URI!
 );
 
-export const HCID_AUTH_URL = "https://auth.hackclub.com/oauth/authorize";
-export const HCID_TOKEN_URL = "https://auth.hackclub.com/oauth/token";
-export const HCID_USER_INFO_URL = "https://auth.hackclub.com/api/v1/me";
+export const HCID_AUTH_URL = 'https://auth.hackclub.com/oauth/authorize';
+export const HCID_TOKEN_URL = 'https://auth.hackclub.com/oauth/token';
+export const HCID_USER_INFO_URL = 'https://auth.hackclub.com/api/v1/me';
 
 export const lucia = new Lucia(adapter, {
   sessionCookie: {
@@ -29,6 +29,8 @@ export const lucia = new Lucia(adapter, {
       slack_id: attributes.slack_id,
       email: attributes.email,
       pfpUrl: attributes.pfpUrl,
+      hackClubVerificationResult: attributes.hackClubVerificationResult,
+      hackClubVerificationCheckedAt: attributes.hackClubVerificationCheckedAt,
       hasOnboarded: attributes.hasOnboarded,
       personalChannelId: attributes.personalChannelId,
       isAdmin: attributes.isAdmin,
@@ -47,6 +49,8 @@ interface DatabaseUserAttributes {
   slack_id: string;
   email: string | null;
   pfpUrl: string;
+  hackClubVerificationResult: string | null;
+  hackClubVerificationCheckedAt: Date | null;
   hasOnboarded: boolean;
   personalChannelId: string | null;
   isAdmin: boolean;
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 0fda63e..41ddb1a 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -354,6 +354,9 @@ importers:
       '@types/node':
         specifier: ^24.0.1
         version: 24.10.4
+      tsx:
+        specifier: ^4.7.1
+        version: 4.21.0
       typescript:
         specifier: ^5.8.2
         version: 5.9.3
@@ -13331,8 +13334,8 @@ snapshots:
       '@typescript-eslint/parser': 8.51.0(eslint@8.57.1)(typescript@5.9.3)
       eslint: 8.57.1
       eslint-import-resolver-node: 0.3.9
-      eslint-import-resolver-typescript: 3.10.1(eslint-plugin-import@2.32.0)(eslint@8.57.1)
-      eslint-plugin-import: 2.32.0(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint-import-resolver-typescript@3.10.1)(eslint@8.57.1)
+      eslint-import-resolver-typescript: 3.10.1(eslint-plugin-import@2.32.0(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint@8.57.1))(eslint@8.57.1)
+      eslint-plugin-import: 2.32.0(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint-import-resolver-typescript@3.10.1(eslint-plugin-import@2.32.0(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint@8.57.1))(eslint@8.57.1))(eslint@8.57.1)
       eslint-plugin-jsx-a11y: 6.10.2(eslint@8.57.1)
       eslint-plugin-react: 7.37.5(eslint@8.57.1)
       eslint-plugin-react-hooks: 5.2.0(eslint@8.57.1)
@@ -13351,7 +13354,7 @@ snapshots:
     transitivePeerDependencies:
       - supports-color
 
-  eslint-import-resolver-typescript@3.10.1(eslint-plugin-import@2.32.0)(eslint@8.57.1):
+  eslint-import-resolver-typescript@3.10.1(eslint-plugin-import@2.32.0(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint@8.57.1))(eslint@8.57.1):
     dependencies:
       '@nolyfill/is-core-module': 1.0.39
       debug: 4.4.3
@@ -13362,22 +13365,22 @@ snapshots:
       tinyglobby: 0.2.15
       unrs-resolver: 1.11.1
     optionalDependencies:
-      eslint-plugin-import: 2.32.0(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint-import-resolver-typescript@3.10.1)(eslint@8.57.1)
+      eslint-plugin-import: 2.32.0(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint-import-resolver-typescript@3.10.1(eslint-plugin-import@2.32.0(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint@8.57.1))(eslint@8.57.1))(eslint@8.57.1)
     transitivePeerDependencies:
       - supports-color
 
-  eslint-module-utils@2.12.1(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.10.1)(eslint@8.57.1):
+  eslint-module-utils@2.12.1(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.10.1(eslint-plugin-import@2.32.0(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint@8.57.1))(eslint@8.57.1))(eslint@8.57.1):
     dependencies:
       debug: 3.2.7
     optionalDependencies:
       '@typescript-eslint/parser': 8.51.0(eslint@8.57.1)(typescript@5.9.3)
       eslint: 8.57.1
       eslint-import-resolver-node: 0.3.9
-      eslint-import-resolver-typescript: 3.10.1(eslint-plugin-import@2.32.0)(eslint@8.57.1)
+      eslint-import-resolver-typescript: 3.10.1(eslint-plugin-import@2.32.0(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint@8.57.1))(eslint@8.57.1)
     transitivePeerDependencies:
       - supports-color
 
-  eslint-plugin-import@2.32.0(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint-import-resolver-typescript@3.10.1)(eslint@8.57.1):
+  eslint-plugin-import@2.32.0(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint-import-resolver-typescript@3.10.1(eslint-plugin-import@2.32.0(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint@8.57.1))(eslint@8.57.1))(eslint@8.57.1):
     dependencies:
       '@rtsao/scc': 1.1.0
       array-includes: 3.1.9
@@ -13388,7 +13391,7 @@ snapshots:
       doctrine: 2.1.0
       eslint: 8.57.1
       eslint-import-resolver-node: 0.3.9
-      eslint-module-utils: 2.12.1(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.10.1)(eslint@8.57.1)
+      eslint-module-utils: 2.12.1(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@3.10.1(eslint-plugin-import@2.32.0(@typescript-eslint/parser@8.51.0(eslint@8.57.1)(typescript@5.9.3))(eslint@8.57.1))(eslint@8.57.1))(eslint@8.57.1)
       hasown: 2.0.2
       is-core-module: 2.16.1
       is-glob: 4.0.3