diff --git a/packages/server-nest/src/modules/Auth/Auth.interfaces.ts b/packages/server-nest/src/modules/Auth/Auth.interfaces.ts
new file mode 100644
index 000000000..a483e5e0e
--- /dev/null
+++ b/packages/server-nest/src/modules/Auth/Auth.interfaces.ts
@@ -0,0 +1,5 @@
+export interface IAuthSignedInEventPayload {}
+
+export interface IAuthSigningInEventPayload {}
+
+export interface IAuthSignInPOJO {}
diff --git a/packages/server-nest/src/modules/Auth/AuthApplication.sevice.ts b/packages/server-nest/src/modules/Auth/AuthApplication.sevice.ts
index e69de29bb..d93cf0dfc 100644
--- a/packages/server-nest/src/modules/Auth/AuthApplication.sevice.ts
+++ b/packages/server-nest/src/modules/Auth/AuthApplication.sevice.ts
@@ -0,0 +1,29 @@
+import { AuthForgetPasswordService } from './AuthForgetPassword.service';
+import { AuthSendResetPasswordService } from './AuthResetPassword.service';
+import { AuthSigninService } from './AuthSignin.service';
+import { AuthSignupService } from './AuthSignup.service';
+
+export class AuthApplication {
+  constructor(
+    private readonly authSigninService: AuthSigninService,
+    private readonly authSignupService: AuthSignupService,
+    private readonly authResetPasswordService: AuthSendResetPasswordService,
+    private readonly authForgetPasswordService: AuthForgetPasswordService,
+  ) {}
+
+  async signin(email: string, password: string) {
+    return this.authSigninService.signIn(email, password);
+  }
+
+  async signup(data: any) {
+    return this.authSignupService.signup(data);
+  }
+
+  async resetPassword(data: any) {
+    return this.authResetPasswordService.resetPassword(data);
+  }
+
+  async forgetPassword(data: any) {
+    return this.authForgetPasswordService.execute(data);
+  }
+}
diff --git a/packages/server-nest/src/modules/Auth/AuthForgetPassword.service.ts b/packages/server-nest/src/modules/Auth/AuthForgetPassword.service.ts
index e69de29bb..eb21b7992 100644
--- a/packages/server-nest/src/modules/Auth/AuthForgetPassword.service.ts
+++ b/packages/server-nest/src/modules/Auth/AuthForgetPassword.service.ts
@@ -0,0 +1 @@
+export class AuthForgetPasswordService {}
diff --git a/packages/server-nest/src/modules/Auth/AuthResetPassword.service.ts b/packages/server-nest/src/modules/Auth/AuthResetPassword.service.ts
index e69de29bb..02d38d867 100644
--- a/packages/server-nest/src/modules/Auth/AuthResetPassword.service.ts
+++ b/packages/server-nest/src/modules/Auth/AuthResetPassword.service.ts
@@ -0,0 +1,132 @@
+import { Injectable, Inject } from '@nestjs/common';
+import uniqid from 'uniqid';
+import moment from 'moment';
+import config from '@/config';
+import {
+  IAuthResetedPasswordEventPayload,
+  IAuthSendedResetPassword,
+  IAuthSendingResetPassword,
+  IPasswordReset,
+  ISystemUser,
+} from '@/interfaces';
+import { EventPublisher } from '@/lib/EventPublisher/EventPublisher';
+import events from '@/subscribers/events';
+import { PasswordReset } from '@/system/models';
+import { ERRORS } from './_constants';
+import { ServiceError } from '@/exceptions';
+import { hashPassword } from '@/utils';
+
+@Injectable()
+export class AuthSendResetPasswordService {
+  constructor(
+    private readonly eventPublisher: EventPublisher,
+    @Inject('SystemUserRepository') private readonly systemUserRepository: any,
+
+    @Inject('PasswordResetModel')
+    private readonly passwordResetModel: typeof PasswordReset,
+  ) {}
+
+  /**
+   * Generates and retrieve password reset token for the given user email.
+   * @param {string} email
+   * @return {<Promise<IPasswordReset>}
+   */
+  public async sendResetPassword(email: string): Promise<PasswordReset> {
+    const user = await this.validateEmailExistance(email);
+
+    const token: string = uniqid();
+
+    // Triggers sending reset password event.
+    await this.eventPublisher.emitAsync(events.auth.sendingResetPassword, {
+      user,
+      token,
+    } as IAuthSendingResetPassword);
+
+    // Delete all stored tokens of reset password that associate to the give email.
+    this.deletePasswordResetToken(email);
+
+    // Creates a new password reset row with unique token.
+    const passwordReset = await this.passwordResetModel
+      .query()
+      .insert({ email, token });
+
+    // Triggers sent reset password event.
+    await this.eventPublisher.emitAsync(events.auth.sendResetPassword, {
+      user,
+      token,
+    } as IAuthSendedResetPassword);
+
+    return passwordReset;
+  }
+
+  /**
+   * Resets a user password from given token.
+   * @param {string} token - Password reset token.
+   * @param {string} password - New Password.
+   * @return {Promise<void>}
+   */
+  public async resetPassword(token: string, password: string): Promise<void> {
+    // Finds the password reset token.
+    const tokenModel: IPasswordReset = await this.passwordResetModel
+      .query()
+      .findOne('token', token);
+    // In case the password reset token not found throw token invalid error..
+    if (!tokenModel) {
+      throw new ServiceError(ERRORS.TOKEN_INVALID);
+    }
+    // Different between token creation datetime and current time.
+    if (
+      moment().diff(tokenModel.createdAt, 'seconds') >
+      config.resetPasswordSeconds
+    ) {
+      // Deletes the expired token by expired token email.
+      await this.deletePasswordResetToken(tokenModel.email);
+      throw new ServiceError(ERRORS.TOKEN_EXPIRED);
+    }
+    const user = await this.systemUserRepository.findOneByEmail(
+      tokenModel.email,
+    );
+
+    if (!user) {
+      throw new ServiceError(ERRORS.USER_NOT_FOUND);
+    }
+    const hashedPassword = await hashPassword(password);
+
+    await this.systemUserRepository.update(
+      { password: hashedPassword },
+      { id: user.id },
+    );
+    // Deletes the used token.
+    await this.deletePasswordResetToken(tokenModel.email);
+
+    // Triggers `onResetPassword` event.
+    await this.eventPublisher.emitAsync(events.auth.resetPassword, {
+      user,
+      token,
+      password,
+    } as IAuthResetedPasswordEventPayload);
+  }
+
+  /**
+   * Deletes the password reset token by the given email.
+   * @param {string} email
+   * @returns {Promise}
+   */
+  private async deletePasswordResetToken(email: string) {
+    return this.passwordResetModel.query().where('email', email).delete();
+  }
+
+  /**
+   * Validates the given email existance on the storage.
+   * @throws {ServiceError}
+   * @param {string} email - email address.
+   */
+  private async validateEmailExistance(email: string): Promise<ISystemUser> {
+    const userByEmail = await this.systemUserRepository.findOneByEmail(email);
+
+    if (!userByEmail) {
+      throw new ServiceError(ERRORS.EMAIL_NOT_FOUND);
+    }
+    return userByEmail;
+  }
+}
diff --git a/packages/server-nest/src/modules/Auth/AuthSignin.service.ts b/packages/server-nest/src/modules/Auth/AuthSignin.service.ts
index 139597f9c..c50ff9054 100644
--- a/packages/server-nest/src/modules/Auth/AuthSignin.service.ts
+++ b/packages/server-nest/src/modules/Auth/AuthSignin.service.ts
@@ -1,2 +1,88 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { cloneDeep } from 'lodash';
+import { SystemUser } from '../System/models/SystemUser';
+import { TenantModel } from '../System/models/TenantModel';
+import { EventEmitter2 } from '@nestjs/event-emitter';
+import { events } from '@/common/events/events';
+import { ServiceError } from '../Items/ServiceError';
+import { ERRORS } from '../Items/Items.constants';
+import {
+  IAuthSignedInEventPayload,
+  IAuthSigningInEventPayload,
+  IAuthSignInPOJO,
+} from './Auth.interfaces';
 
+@Injectable()
+export class AuthSigninService {
+  constructor(
+    private readonly eventEmitter: EventEmitter2,
 
+    @Inject(SystemUser.name)
+    private readonly systemUserModel: typeof SystemUser,
+
+    @Inject(TenantModel.name)
+    private readonly tenantModel: typeof TenantModel,
+  ) {}
+
+  /**
+   * Validates the given email and password.
+   * @param {ISystemUser} user
+   */
+  public async validateSignIn(user: SystemUser) {
+    // Validate if the given user is inactive.
+    if (!user.active) {
+      throw new ServiceError(ERRORS.USER_INACTIVE);
+    }
+  }
+
+  /**
+   * sign-in and generates JWT token.
+   * @param {string} email - Email address.
+   * @param {string} password - Password.
+   * @return {Promise<{user: IUser, token: string}>}
+   */
+  public async signIn(
+    email: string,
+    password: string,
+  ): Promise<IAuthSignInPOJO> {
+    // Finds the user of the given email address.
+    const user = await SystemUser.query()
+      .findOne('email', email)
+      .modify('inviteAccepted');
+
+    // Validate the given email and password.
+    await this.validateSignIn(user);
+
+    // Triggers on signing-in event.
+    await this.eventEmitter.emitAsync(events.auth.signingIn, {
+      email,
+      password,
+      user,
+    } as IAuthSigningInEventPayload);
+
+    const token = generateToken(user);
+
+    // Update the last login at of the user.
+    // await systemUserRepository.patchLastLoginAt(user.id);
+
+    // Triggers `onSignIn` event.
+    await this.eventEmitter.emitAsync(events.auth.signIn, {
+      email,
+      password,
+      user,
+    } as IAuthSignedInEventPayload);
+
+    const tenant = await this.tenantModel
+      .query()
+      .findById(user.tenantId)
+      .withGraphFetched('metadata');
+
+    // Keep the user object immutable.
+    const outputUser = cloneDeep(user);
+
+    // Remove password property from user object.
+    Reflect.deleteProperty(outputUser, 'password');
+
+    return { user: outputUser, token, tenant };
+  }
+}
diff --git a/packages/server-nest/src/modules/Auth/AuthSignup.service.ts b/packages/server-nest/src/modules/Auth/AuthSignup.service.ts
index e69de29bb..873b010c1 100644
--- a/packages/server-nest/src/modules/Auth/AuthSignup.service.ts
+++ b/packages/server-nest/src/modules/Auth/AuthSignup.service.ts
@@ -0,0 +1 @@
+export class AuthSignupService {}