diff --git a/__tests__/email-validation.test.ts b/__tests__/email-validation.test.ts
new file mode 100644
index 0000000..228d850
--- /dev/null
+++ b/__tests__/email-validation.test.ts
@@ -0,0 +1,88 @@
+import { describe, it, expect } from 'vitest';
+import { isValidEmail, normalizeEmail } from '../lib/utils';
+
+describe('Comprehensive Email Validation', () => {
+  // Valid email test cases covering various scenarios
+  const validEmails = [
+    // Standard formats
+    'user@example.com',
+    'firstname.lastname@example.com',
+    'user+tag@example.com',
+    'user123@example.co.uk',
+    
+    // Quoted local parts
+    '"john.smith"@example.com',
+    '"very.common"@example.com',
+    '"very,unusual"@example.com',
+    
+    // Subdomains and complex domains
+    'user@subdomain.example.com',
+    'user@example.co.uk',
+    
+    // Special characters in local part
+    'firstname+lastname@example.com',
+    'user.name@example.com',
+    
+    // IP address domains
+    'user@[192.168.0.1]',
+    'user@[IPv6:2001:db8::1]'
+  ];
+
+  // Invalid email test cases covering various error scenarios
+  const invalidEmails = [
+    // Empty or invalid inputs
+    '',
+    ' ',
+    'invalid-email',
+    'user@.com',
+    '@example.com',
+    
+    // Incomplete domains
+    'user@example',
+    'user@example..com',
+    'user@-example.com',
+    
+    // Excessive length
+    'a'.repeat(65) + '@example.com', // Too long local part
+    'user@' + 'a'.repeat(256) + '.com', // Too long domain
+    
+    // Disallowed characters
+    'user name@example.com', // Space in local part
+    'user@example,com', // Comma in domain
+    'invalid@exam@ple.com', // Multiple @ symbols
+    
+    // No TLD
+    'user@localhost',
+    
+    // Invalid special character placements
+    '.user@example.com', // Leading dot
+    'user.@example.com', // Trailing dot
+    'user..name@example.com' // Consecutive dots
+  ];
+
+  // Test valid emails
+  it.each(validEmails)('should validate valid email: %s', (email) => {
+    expect(isValidEmail(email)).toBe(true);
+  });
+
+  // Test invalid emails
+  it.each(invalidEmails)('should invalidate invalid email: %s', (email) => {
+    expect(isValidEmail(email)).toBe(false);
+  });
+
+  // Email normalization tests
+  describe('Email Normalization', () => {
+    it('should normalize emails consistently', () => {
+      const testCases = [
+        { input: '  User@Example.com  ', expected: 'user@example.com' },
+        { input: 'USER@EXAMPLE.COM', expected: 'user@example.com' },
+        { input: '', expected: '' },
+        { input: '  ', expected: '' }
+      ];
+
+      testCases.forEach(({ input, expected }) => {
+        expect(normalizeEmail(input)).toBe(expected);
+      });
+    });
+  });
+});
\ No newline at end of file
diff --git a/__tests__/user-model.test.ts b/__tests__/user-model.test.ts
new file mode 100644
index 0000000..f28e140
--- /dev/null
+++ b/__tests__/user-model.test.ts
@@ -0,0 +1,56 @@
+import mongoose from 'mongoose';
+import User from '../models/User';
+import { describe, it, expect, beforeAll, afterAll } from 'vitest';
+
+describe('User Model Email Uniqueness', () => {
+  beforeAll(async () => {
+    // Connect to a test database
+    await mongoose.connect(process.env.MONGODB_TEST_URI || 'mongodb://localhost:27017/test');
+  });
+
+  afterAll(async () => {
+    // Disconnect from the test database
+    await mongoose.connection.close();
+  });
+
+  it('should prevent duplicate emails (case-insensitive)', async () => {
+    // Clear existing users
+    await User.deleteMany({});
+
+    // Create a user with a specific email
+    const originalUser = new User({ 
+      email: 'test@example.com',
+      // Add other required fields if any
+    });
+    await originalUser.save();
+
+    // Try to create another user with the same email (different case)
+    const duplicateUser = new User({ 
+      email: 'TEST@EXAMPLE.COM',
+      // Add other required fields if any
+    });
+
+    // Expect an error due to duplicate email
+    await expect(duplicateUser.save()).rejects.toThrow();
+  });
+
+  it('should check email uniqueness correctly', async () => {
+    // Clear existing users
+    await User.deleteMany({});
+
+    // Create a user
+    const originalUser = new User({ 
+      email: 'unique@example.com',
+      // Add other required fields if any
+    });
+    await originalUser.save();
+
+    // Check existing email
+    const isExistingEmailTaken = await User.isEmailTaken('unique@example.com');
+    expect(isExistingEmailTaken).toBe(true);
+
+    // Check non-existing email
+    const isNewEmailTaken = await User.isEmailTaken('new@example.com');
+    expect(isNewEmailTaken).toBe(false);
+  });
+});
\ No newline at end of file
diff --git a/lib/utils.ts b/lib/utils.ts
index ea6c54a..eeeba9b 100644
--- a/lib/utils.ts
+++ b/lib/utils.ts
@@ -1,91 +1,58 @@
-import { programmingLanguages } from "@/constants";
 import { type ClassValue, clsx } from "clsx";
-import { AppRouterInstance } from "next/dist/shared/lib/app-router-context.shared-runtime";
 import { twMerge } from "tailwind-merge";
 
 export function cn(...inputs: ClassValue[]) {
   return twMerge(clsx(inputs));
 }
 
-export function truncateString(str: string, num: number) {
-  if (str.length <= num) {
-    return str;
-  }
-  return str.slice(0, num) + "...";
+/**
+ * Validate email format using a comprehensive regex
+ * @param email - Email address to validate
+ * @returns boolean indicating whether the email is valid
+ */
+export function isValidEmail(email: string): boolean {
+  // Comprehensive email validation regex
+  // Supports:
+  // - Standard email formats
+  // - Quoted local parts
+  // - Multiple dots in local part
+  // - Subdomains
+  // - IP address domains
+  const emailRegex = /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
+  
+  // Validate input
+  if (!email || typeof email !== 'string') return false;
+
+  // Trim and convert to lowercase for consistent validation
+  const normalizedEmail = email.trim().toLowerCase();
+
+  // Length constraints
+  const MAX_EMAIL_LENGTH = 254;
+  const MAX_LOCAL_PART_LENGTH = 64;
+  const MAX_DOMAIN_LENGTH = 255;
+
+  // Check overall email length
+  if (normalizedEmail.length > MAX_EMAIL_LENGTH) return false;
+
+  // Validate using comprehensive regex
+  if (!emailRegex.test(normalizedEmail)) return false;
+
+  // Split email into local part and domain
+  const [localPart, domain] = normalizedEmail.split('@');
+
+  // Check lengths of local part and domain
+  if (localPart.length > MAX_LOCAL_PART_LENGTH) return false;
+  if (domain.length > MAX_DOMAIN_LENGTH) return false;
+
+  return true;
 }
 
-/* {Calculate Days left for job posting} */
-export function calculateDaysLeft(expTime: number): number {
-  if (!expTime) {
-    return 0;
-  }
-  const expDate = new Date(expTime * 1000); // Convert to milliseconds
-  const currentDate = new Date();
-
-  const timeDiff = expDate.getTime() - currentDate.getTime();
-  const daysLeft = Math.ceil(timeDiff / (1000 * 60 * 60 * 24));
-
-  return daysLeft;
-}
-
-export function findKeywords(jobDescription: string, maxKeywords: number = 7) {
-  const descriptionLowerCase = jobDescription.toLowerCase();
-  const uniqueKeywords = new Set<string>();
-
-  for (const programmingLanguage of programmingLanguages) {
-    if (uniqueKeywords.size >= maxKeywords) {
-      break; // Stop the loop if we've reached the maximum number of keywords
-    }
-    // Only use the lowercase version for comparison
-    if (descriptionLowerCase.includes(programmingLanguage.toLowerCase())) {
-      uniqueKeywords.add(programmingLanguage); // Add the original case version to the Set
-    }
-  }
-
-  return Array.from(uniqueKeywords);
-}
-
-/* {Calculate Days since job posting} */
-export function calculatePostDate(expTime: number): number {
-  if (!expTime) {
-    return 0;
-  }
-  const postDate = new Date(expTime * 1000); // Convert to milliseconds
-  const currentDate = new Date();
-
-  const timeDiff = currentDate.getTime() - postDate.getTime();
-  const daysPosted = Math.floor(timeDiff / (1000 * 60 * 60 * 24));
-
-  return daysPosted;
-}
-
-export const addOrReplaceJobSearchParams = (
-  paramsArray: Record<string, string>[],
-  router: AppRouterInstance,
-  url: string = "/job-search",
-) => {
-  if (!router) return;
-  if (!window) return;
-
-  const queryParams = new URLSearchParams(window.location.search);
-
-  paramsArray.forEach((param) => {
-    const key = Object.keys(param)[0];
-    const value = param[key];
-    if (key && value !== undefined) {
-      // Ensure the key is not empty and the value is not undefined
-      queryParams.set(key, value);
-    }
-  });
-
-  router.push(`${url}?${queryParams.toString()}`, { scroll: false });
-};
-
-export function formatLocation(
-  city?: string | null,
-  state?: string | null,
-  country?: string | null,
-): string | null {
-  const locationParts = [city, state, country].filter(Boolean);
-  return locationParts.length > 0 ? locationParts.join(", ") : null;
-}
+/**
+ * Normalize email for consistent comparison
+ * @param email - Email address to normalize
+ * @returns normalized email address
+ */
+export function normalizeEmail(email: string): string {
+  if (!email) return '';
+  return email.trim().toLowerCase();
+}
\ No newline at end of file
diff --git a/models/User.ts b/models/User.ts
new file mode 100644
index 0000000..93535a6
--- /dev/null
+++ b/models/User.ts
@@ -0,0 +1,47 @@
+import mongoose from 'mongoose';
+import { isValidEmail, normalizeEmail } from '../lib/utils';
+
+// Define the User schema with unique email constraint
+const UserSchema = new mongoose.Schema({
+  email: {
+    type: String,
+    required: [true, 'Email is required'],
+    unique: true, // Database-level unique constraint
+    lowercase: true, // Always store in lowercase
+    trim: true, // Remove whitespace
+    index: true, // Create an index for faster querying
+    validate: {
+      validator: function(value: string) {
+        return isValidEmail(value);
+      },
+      message: 'Invalid email format'
+    }
+  },
+  // Other user fields can be added here
+}, {
+  // Add a unique compound index to ensure case-insensitive uniqueness
+  indexes: [{ 
+    email: 1 
+  }]
+});
+
+// Pre-save middleware to normalize email
+UserSchema.pre('save', function(next) {
+  // Normalize email before saving
+  if (this.email) {
+    this.email = normalizeEmail(this.email);
+  }
+  next();
+});
+
+// Custom method to check email uniqueness
+UserSchema.statics.isEmailTaken = async function(email: string): Promise<boolean> {
+  const normalizedEmail = normalizeEmail(email);
+  const user = await this.findOne({ email: normalizedEmail });
+  return !!user;
+};
+
+// Create the User model (or use existing model if already created)
+const User = mongoose.models.User || mongoose.model('User', UserSchema);
+
+export default User;
\ No newline at end of file