diff --git a/src/controllers/auth.ts b/src/controllers/auth.ts
index 2c6fbcb..f49eed3 100644
--- a/src/controllers/auth.ts
+++ b/src/controllers/auth.ts
@@ -1,6 +1,5 @@
 import { Security, Route, Tags, Example, Post, Body, Query, Hidden } from 'tsoa'
 import jwt from 'jsonwebtoken'
-import bcrypt from 'bcryptjs'
 import User from '../model/User'
 import { InfoJWT } from '../types'
 import { removeTokensInDB, saveTokensInDB } from '../utils'
@@ -80,7 +79,7 @@ const authorize = async (data: any): Promise<AuthorizeResponse> => {
   const user = await User.findOne({ username })
   if (!user) throw new Error('Username is not found.')
 
-  const validPass = await bcrypt.compare(password, user.password)
+  const validPass = user.comparePassword(password)
   if (!validPass) throw new Error('Invalid password.')
 
   // generate authorization code against clientId
diff --git a/src/controllers/group.ts b/src/controllers/group.ts
index 7cd7aa2..98a9467 100644
--- a/src/controllers/group.ts
+++ b/src/controllers/group.ts
@@ -163,7 +163,10 @@ const createGroup = async ({
 }
 
 const getGroup = async (groupId: number): Promise<GroupDetailsResponse> => {
-  const group = (await Group.findOne({ groupId }).populate(
+  const group = (await Group.findOne(
+    { groupId },
+    'groupId name description isActive users -_id'
+  ).populate(
     'users',
     'id username displayName -_id'
   )) as unknown as GroupDetailsResponse
@@ -193,7 +196,13 @@ const addUserToGroup = async (
   )) as unknown as GroupDetailsResponse
   if (!updatedGroup) throw new Error('Unable to update group')
 
-  return updatedGroup
+  return {
+    groupId: updatedGroup.groupId,
+    name: updatedGroup.name,
+    description: updatedGroup.description,
+    isActive: updatedGroup.isActive,
+    users: updatedGroup.users
+  }
 }
 
 const removeUserFromGroup = async (
@@ -211,5 +220,11 @@ const removeUserFromGroup = async (
   )) as unknown as GroupDetailsResponse
   if (!updatedGroup) throw new Error('Unable to update group')
 
-  return updatedGroup
+  return {
+    groupId: updatedGroup.groupId,
+    name: updatedGroup.name,
+    description: updatedGroup.description,
+    isActive: updatedGroup.isActive,
+    users: updatedGroup.users
+  }
 }
diff --git a/src/controllers/user.ts b/src/controllers/user.ts
index 5e4573c..b47d666 100644
--- a/src/controllers/user.ts
+++ b/src/controllers/user.ts
@@ -12,7 +12,6 @@ import {
   Body,
   Hidden
 } from 'tsoa'
-import bcrypt from 'bcryptjs'
 
 import User, { UserPayload } from '../model/User'
 
@@ -131,8 +130,7 @@ const createUser = async (data: UserPayload): Promise<UserDetailsResponse> => {
   if (usernameExist) throw new Error('Username already exists.')
 
   // Hash passwords
-  const salt = await bcrypt.genSalt(10)
-  const hashPassword = await bcrypt.hash(password, salt)
+  const hashPassword = User.hashPassword(password)
 
   // Create a new user
   const user = new User({
@@ -180,8 +178,7 @@ const updateUser = async (
 
   if (password) {
     // Hash passwords
-    const salt = await bcrypt.genSalt(10)
-    params.password = await bcrypt.hash(password, salt)
+    params.password = User.hashPassword(password)
   }
 
   const updatedUser = await User.findOneAndUpdate({ id }, params, { new: true })
@@ -208,7 +205,7 @@ const deleteUser = async (
   if (!user) throw new Error('User is not found.')
 
   if (!isAdmin) {
-    const validPass = await bcrypt.compare(password!, user.password)
+    const validPass = user.comparePassword(password!)
     if (!validPass) throw new Error('Invalid password.')
   }
 
diff --git a/src/model/Group.ts b/src/model/Group.ts
index c081894..8ff04ff 100644
--- a/src/model/Group.ts
+++ b/src/model/Group.ts
@@ -31,7 +31,7 @@ interface IGroup extends IGroupDocument {
 }
 interface IGroupModel extends Model<IGroup> {}
 
-const groupSchema = new Schema({
+const groupSchema = new Schema<IGroupDocument>({
   name: {
     type: String,
     required: true
diff --git a/src/model/User.ts b/src/model/User.ts
index 589f4f5..61521b5 100644
--- a/src/model/User.ts
+++ b/src/model/User.ts
@@ -1,5 +1,6 @@
-import mongoose, { Schema, model } from 'mongoose'
+import mongoose, { Schema, model, Document, Model } from 'mongoose'
 const AutoIncrement = require('mongoose-sequence')(mongoose)
+import bcrypt from 'bcryptjs'
 
 export interface UserPayload {
   /**
@@ -28,7 +29,7 @@ export interface UserPayload {
   isActive?: boolean
 }
 
-interface User extends UserPayload {
+interface IUserDocument extends UserPayload, Document {
   id: number
   isAdmin: boolean
   isActive: boolean
@@ -36,7 +37,14 @@ interface User extends UserPayload {
   tokens: [{ [key: string]: string }]
 }
 
-const UserSchema = new Schema<User>({
+interface IUser extends IUserDocument {
+  comparePassword(password: string): boolean
+}
+interface IUserModel extends Model<IUser> {
+  hashPassword(password: string): string
+}
+
+const userSchema = new Schema<IUserDocument>({
   displayName: {
     type: String,
     required: true
@@ -76,6 +84,20 @@ const UserSchema = new Schema<User>({
     }
   ]
 })
-UserSchema.plugin(AutoIncrement, { inc_field: 'id' })
+userSchema.plugin(AutoIncrement, { inc_field: 'id' })
 
-export default model('User', UserSchema)
+// Static Methods
+userSchema.static('hashPassword', (password: string): string => {
+  const salt = bcrypt.genSaltSync(10)
+  return bcrypt.hashSync(password, salt)
+})
+
+// Instance Methods
+userSchema.method('comparePassword', function (password: string): boolean {
+  if (bcrypt.compareSync(password, this.password)) return true
+  return false
+})
+
+export const User: IUserModel = model<IUser, IUserModel>('User', userSchema)
+
+export default User
diff --git a/src/routes/api/auth.ts b/src/routes/api/auth.ts
index 8aedd32..b16e302 100644
--- a/src/routes/api/auth.ts
+++ b/src/routes/api/auth.ts
@@ -1,6 +1,5 @@
 import express from 'express'
 import mongoose from 'mongoose'
-import jwt from 'jsonwebtoken'
 
 import AuthController from '../../controllers/auth'
 import Client from '../../model/Client'
@@ -10,12 +9,7 @@ import {
   authenticateRefreshToken
 } from '../../middlewares'
 
-import {
-  authorizeValidation,
-  removeTokensInDB,
-  saveTokensInDB,
-  tokenValidation
-} from '../../utils'
+import { authorizeValidation, tokenValidation } from '../../utils'
 import { InfoJWT } from '../../types'
 
 const authRouter = express.Router()