diff --git a/.prettierrc b/.prettierrc
new file mode 100644
index 0000000..6d37fb6
--- /dev/null
+++ b/.prettierrc
@@ -0,0 +1,13 @@
+{
+  "arrowParens": "always",
+  "embeddedLanguageFormatting": "off",
+  "endOfLine": "auto",
+  "jsxBracketSameLine": false,
+  "jsxSingleQuote": true,
+  "printWidth": 100,
+  "semi": true,
+  "singleQuote": true,
+  "tabWidth": 2,
+  "trailingComma": "all",
+  "useTabs": false  
+}
diff --git a/src/Dtos/address.dto.ts b/src/Dtos/address.dto.ts
index 7c83c70..afdfe89 100644
--- a/src/Dtos/address.dto.ts
+++ b/src/Dtos/address.dto.ts
@@ -1,16 +1,21 @@
-import { ApiProperty } from "@nestjs/swagger";
+import { ApiProperty } from '@nestjs/swagger';
 
 export class AddressDto {
-    @ApiProperty()
-    address1: string;
-    @ApiProperty()
-    address2: string;
-    @ApiProperty()
-    city: string;
-    @ApiProperty()
-    state: string;
-    @ApiProperty()
-    zip: string;
-    @ApiProperty()
-    country: string;
+  @ApiProperty()
+  address1: string;
+
+  @ApiProperty()
+  address2?: string;
+
+  @ApiProperty()
+  city: string;
+
+  @ApiProperty()
+  country: string;
+
+  @ApiProperty()
+  state: string;
+
+  @ApiProperty()
+  zip: string;
 }
diff --git a/src/Dtos/customer.dto.ts b/src/Dtos/customer.dto.ts
index 57a6112..404cd3a 100644
--- a/src/Dtos/customer.dto.ts
+++ b/src/Dtos/customer.dto.ts
@@ -1,38 +1,53 @@
-import { ApiProperty } from "@nestjs/swagger";
+import { ApiProperty } from '@nestjs/swagger';
 import { DriverLicenseDto } from './driveLicense.dto';
 import { AddressDto } from './address.dto';
 
 export class CustomerDto {
-    @ApiProperty()
-    customerId: string;
-    @ApiProperty()
-    externalId: string;
-    @ApiProperty()
-    merchantId: string;
-    @ApiProperty()
-    name: string;
-    @ApiProperty()
-    vip: string;
-    @ApiProperty()
-    taxId: string;
-    @ApiProperty()
-    driverLicense: DriverLicenseDto;
-    @ApiProperty()
-    address: AddressDto;
-    @ApiProperty()
-    phone: string;
-    @ApiProperty()
-    email: string;
-    @ApiProperty()
-    balance: any;
-    @ApiProperty()
-    currency: any;
-    @ApiProperty()
-    enrollDate: number;
-    @ApiProperty()
-    dateOfBirth: number;
-    @ApiProperty()
-    createdAt: number;
-    @ApiProperty()
-    updatedAt: number;
+  @ApiProperty()
+  address: AddressDto;
+
+  @ApiProperty()
+  balance?: string;
+
+  @ApiProperty()
+  createdAt: number;
+
+  @ApiProperty()
+  currency?: string;
+
+  @ApiProperty()
+  customerId: string;
+
+  @ApiProperty()
+  dateOfBirth: string;
+
+  @ApiProperty()
+  driverLicense?: DriverLicenseDto;
+
+  @ApiProperty()
+  email: string;
+
+  @ApiProperty()
+  enrollDate: number; // Unix Timestamp
+
+  @ApiProperty()
+  externalId: string;
+
+  @ApiProperty()
+  merchantId: string;
+
+  @ApiProperty()
+  name: string;
+
+  @ApiProperty()
+  phone: string;
+
+  @ApiProperty()
+  taxId: string;
+
+  @ApiProperty()
+  updatedAt: number;
+
+  @ApiProperty()
+  vip?: string;
 }
diff --git a/src/Dtos/establish.dto.ts b/src/Dtos/establish.dto.ts
index c46df36..5708f38 100644
--- a/src/Dtos/establish.dto.ts
+++ b/src/Dtos/establish.dto.ts
@@ -1,4 +1,4 @@
-import { ApiProperty } from "@nestjs/swagger";
+import { ApiProperty } from '@nestjs/swagger';
 import { AccountDto } from './account.dto';
 import { MetaDataDto } from './meta.dto';
 import { RecurrenceDto } from './recurrence.dto';
@@ -6,48 +6,67 @@ import { VerificationDto } from './verification.dto';
 import { CustomerDto } from './customer.dto';
 
 export class EstablishDto {
-    @ApiProperty()
-    accessId: any;
-    @ApiProperty()
-    merchantId: any;
-    @ApiProperty()
-    description: any;
-    @ApiProperty()
-    currency: any;
-    @ApiProperty()
-    amount: any;
-    @ApiProperty()
-    displayAmount: any;
-    @ApiProperty()
-    minimumBalance: any;
-    @ApiProperty()
-    merchantReference: any;
-    @ApiProperty()
-    paymentType: string;
-    @ApiProperty()
-    timeZone: any;
-    @ApiProperty()
-    returnUrl: any;
-    @ApiProperty()
-    cancelUrl: any;
-    @ApiProperty()
-    env: any;
-    @ApiProperty()
-    localUrl: any;
-    @ApiProperty()
-    metadata: MetaDataDto;
-    @ApiProperty()
-    recurrence: RecurrenceDto;
-    @ApiProperty()
-    verification: VerificationDto;
-    @ApiProperty()
-    customer: CustomerDto;
-    @ApiProperty()
-    account: AccountDto;
-    @ApiProperty()
-    transactionId: any;
+  @ApiProperty()
+  accessId: string;
+
+  @ApiProperty()
+  account: AccountDto;
+
+  @ApiProperty()
+  amount: string;
+
+  @ApiProperty()
+  cancelUrl: string;
+
+  @ApiProperty()
+  currency: string;
+
+  @ApiProperty()
+  customer: CustomerDto;
+
+  @ApiProperty()
+  description: string;
+
+  @ApiProperty()
+  displayAmount: string;
+
+  @ApiProperty()
+  env: string;
+
+  @ApiProperty()
+  localUrl: string;
+
+  @ApiProperty()
+  merchantId: string;
+
+  @ApiProperty()
+  merchantReference: string;
+
+  @ApiProperty()
+  metadata: MetaDataDto;
+
+  @ApiProperty()
+  minimumBalance: number;
+
+  @ApiProperty()
+  paymentType: string;
+
+  @ApiProperty()
+  recurrence: RecurrenceDto;
+
+  @ApiProperty()
+  returnUrl: string;
+
+  @ApiProperty()
+  timeZone: any;
+
+  @ApiProperty()
+  transactionId: any;
+
+  @ApiProperty()
+  verification: VerificationDto;
 }
 
 export interface EstablishDto {
-  [key: string]: string | object;
+  [key: string]: number | object | string;
 }
diff --git a/src/Dtos/recurrence.dto.ts b/src/Dtos/recurrence.dto.ts
index 5ede82b..67de028 100644
--- a/src/Dtos/recurrence.dto.ts
+++ b/src/Dtos/recurrence.dto.ts
@@ -1,18 +1,24 @@
-import { ApiProperty } from "@nestjs/swagger";
+import { ApiProperty } from '@nestjs/swagger';
 
 export class RecurrenceDto {
-    @ApiProperty()
-    startDate: any;
-    @ApiProperty()
-    endDate: any;
-    @ApiProperty()
-    frequency: any;
-    @ApiProperty()
-    frequencyUnit: any;
-    @ApiProperty()
-    frequencyUnitType: any;
-    @ApiProperty()
-    recurringAmount: any;
-    @ApiProperty()
-    automaticCapture: any;
+  @ApiProperty()
+  automaticCapture: boolean;
+
+  @ApiProperty()
+  endDate?: number; // Unix Timestamp
+
+  @ApiProperty()
+  frequency?: number;
+
+  @ApiProperty()
+  frequencyUnit: number;
+
+  @ApiProperty()
+  frequencyUnitType: number;
+
+  @ApiProperty()
+  recurringAmount: string;
+
+  @ApiProperty()
+  startDate?: number; // Unix Timestamp
 }
diff --git a/src/RequestSignature/request-signature.utils.spec.ts b/src/RequestSignature/request-signature.utils.spec.ts
index 49eefb5..b3a66bc 100644
--- a/src/RequestSignature/request-signature.utils.spec.ts
+++ b/src/RequestSignature/request-signature.utils.spec.ts
@@ -1,5 +1,180 @@
 import { EstablishDto } from '../Dtos/establish.dto';
-import { normalizeEstablishData } from './request-signature.utils';
+
+import {
+  createSignatureQueryString,
+  generateSignature,
+  normalizeEstablishData,
+} from './request-signature.utils';
+
+describe('generateSignature', () => {
+  const accessId = '123456';
+  const establishData: EstablishDto = {
+    accessId: '1234',
+    account: {
+      accountNumber: '',
+      routingNumber: '',
+      type: 1,
+      // Application specific fields
+      country: '',
+      name: '',
+      nameOnAccount: '',
+      paymentProviderSubtype: 0,
+      profile: 0,
+      source: 0,
+      token: '',
+      verification: {
+        hasEnoughFunds: false,
+        verificationDate: 0,
+        verified: false,
+        type: 0,
+      },
+      verified: false,
+    },
+    amount: '1.00',
+    cancelUrl: '',
+    currency: 'USD',
+    customer: {
+      address: {
+        address1: '123 Main St',
+        city: 'San Francisco',
+        country: 'US',
+        state: 'CA',
+        zip: '94111',
+      },
+      dateOfBirth: '1990-01-01',
+      driverLicense: {
+        number: '1010',
+        state: 'CA',
+      },
+      email: 'john@ca.us',
+      enrollDate: 1234567890,
+      externalId: '1234',
+      name: 'John Doe',
+      phone: '123-456-7890',
+      taxId: '123-45-6789',
+      // Application specific fields
+      createdAt: 0,
+      customerId: '',
+      merchantId: '',
+      updatedAt: 0,
+    },
+    description: 'text',
+    displayAmount: '1.00',
+    localUrl: 'mySite',
+    merchantId: '1234',
+    merchantReference: 'ref123',
+    metadata: {
+      urlScheme: '',
+    },
+    paymentType: 'Recurring',
+    recurrence: {
+      automaticCapture: false,
+      frequencyUnit: 1,
+      frequencyUnitType: 3,
+      recurringAmount: '1.00',
+    },
+    returnUrl: '',
+    transactionId: '',
+    verification: {
+      verifyCustomer: false,
+      // Application specific fields
+      status: '',
+      verified: false,
+    },
+    // Application specific fields
+    env: '',
+    minimumBalance: 0,
+    timeZone: '',
+  };
+
+  it('should generate proper signature', () => {
+    const expectedQueryString =
+      'accessId=1234&merchantId=1234&description=text&currency=USD&amount=1.00&displayAmount=1.00&merchantReference=ref123&paymentType=Recurring&recurrence.frequencyUnit=1&recurrence.frequencyUnitType=3&recurrence.recurringAmount=1.00&customer.externalId=1234&customer.name=John Doe&customer.taxId=123-45-6789&customer.driverLicense.number=1010&customer.driverLicense.state=CA&customer.address.address1=123 Main St&customer.address.city=San Francisco&customer.address.state=CA&customer.address.zip=94111&customer.address.country=US&customer.phone=123-456-7890&customer.email=john@ca.us&customer.enrollDate=1234567890&customer.dateOfBirth=1990-01-01&account.type=1';
+    const expectedSignature = 'HrGQpg/NsPXmh+P9u37R121Rot0=';
+
+    const queryString = createSignatureQueryString(establishData);
+    const signature = generateSignature(establishData, accessId);
+
+    expect(queryString).toEqual(expectedQueryString);
+    expect(signature).toBe(expectedSignature);
+  });
+
+  it('should generate proper signature ignoring empty strings', () => {
+    const establishDataWithEmptyStrings = {
+      ...establishData,
+      displayAmount: '',
+    };
+    const expectedSignature = 'L/tBy40/WKaWNH0dcdp9j09cMqs=';
+
+    const queryString = createSignatureQueryString(establishDataWithEmptyStrings);
+    const signature = generateSignature(establishDataWithEmptyStrings, accessId);
+
+    expect(queryString).not.toContain('transactionId=');
+    expect(signature).toBe(expectedSignature);
+  });
+
+  it('should generate proper signature ignoring not intended data', () => {
+    const establishDataWithNotIntendedData = {
+      ...establishData,
+      notIntendedData: 'notIntendedData',
+    };
+    const expectedSignature = 'HrGQpg/NsPXmh+P9u37R121Rot0=';
+
+    const queryString = createSignatureQueryString(establishDataWithNotIntendedData);
+    const signature = generateSignature(establishDataWithNotIntendedData, accessId);
+
+    expect(queryString).not.toContain('notIntendedData=');
+    expect(signature).toBe(expectedSignature);
+  });
+
+  it('should generate proper signature ignoring false booleans', () => {
+    const establishDataWithFalseBooleans = {
+      ...establishData,
+      recurrence: {
+        ...establishData.recurrence,
+        automaticCapture: false,
+      },
+    };
+    const expectedSignature = 'HrGQpg/NsPXmh+P9u37R121Rot0=';
+
+    const queryString = createSignatureQueryString(establishDataWithFalseBooleans);
+    const signature = generateSignature(establishDataWithFalseBooleans, accessId);
+
+    expect(queryString).not.toContain('recurrence.automaticCapture=');
+    expect(signature).toBe(expectedSignature);
+  });
+
+  it('should create proper query string with first-level nested objects', () => {
+    const establishDataWithNestedObjects = {
+      ...establishData,
+      customer: {
+        ...establishData.customer,
+        dateOfBirth: '2000-01-01',
+      },
+    };
+
+    const queryString = createSignatureQueryString(establishDataWithNestedObjects);
+
+    expect(queryString).toContain('customer.dateOfBirth=2000-01-01');
+  });
+
+  it('should create proper query string with deep nested objects', () => {
+    const establishDataWithNestedObjects = {
+      ...establishData,
+      customer: {
+        ...establishData.customer,
+        address: {
+          ...establishData.customer.address,
+          country: 'BR',
+        },
+      },
+    };
+
+    const queryString = createSignatureQueryString(establishDataWithNestedObjects);
+
+    expect(queryString).toContain('customer.address.country=BR');
+  });
+});
 
 describe('normalizeEstablishData', () => {
   test('converts dot notation into nested object', () => {
diff --git a/src/RequestSignature/request-signature.utils.ts b/src/RequestSignature/request-signature.utils.ts
index 7dbe78f..69fa63d 100644
--- a/src/RequestSignature/request-signature.utils.ts
+++ b/src/RequestSignature/request-signature.utils.ts
@@ -1,84 +1,96 @@
 import { EstablishDto } from '../Dtos/establish.dto';
 import { convertDotNotationIntoNestedObject } from '../utils/normalize';
 
-const CryptoSignature = require('crypto');
+const crypto = require('crypto');
 
-export const generateSignature = (establishData: EstablishDto, accessKey: string) => {
-    let query = '';
-    query += `accessId=${establishData.accessId}`;
-    query += `&merchantId=${establishData.merchantId}`;
-    query += `&description=${establishData.description}`;
-    query += `&currency=${establishData.currency}`;
-    query += `&amount=${establishData.amount}`;
+const signatureKeysOrdered = [
+  'accessId',
+  'merchantId',
+  'description',
+  'currency',
+  'amount',
+  'displayAmount',
+  'minimumBalance',
+  'merchantReference',
+  'paymentType',
+  'timeZone',
+  'recurrence.startDate',
+  'recurrence.endDate',
+  'recurrence.frequency',
+  'recurrence.frequencyUnit',
+  'recurrence.frequencyUnitType',
+  'recurrence.recurringAmount',
+  'recurrence.automaticCapture',
+  'verification.status',
+  'verification.verifyCustomer',
+  'customer.customerId',
+  'customer.externalId',
+  'customer.name',
+  'customer.vip',
+  'customer.taxId',
+  'customer.driverLicense.number',
+  'customer.driverLicense.state',
+  'customer.address.address1',
+  'customer.address.address2',
+  'customer.address.city',
+  'customer.address.state',
+  'customer.address.zip',
+  'customer.address.country',
+  'customer.phone',
+  'customer.email',
+  'customer.balance',
+  'customer.currency',
+  'customer.enrollDate',
+  'customer.externalTier',
+  'customer.dateOfBirth',
+  'account.nameOnAccount',
+  'account.name',
+  'account.type',
+  'account.profile',
+  'account.accountNumber',
+  'account.routingNumber',
+  'transactionId',
+];
 
-    if (establishData.displayAmount) query += `&displayAmount=${establishData.displayAmount}`;
-    if (establishData.minimumBalance) query += `&minimumBalance=${establishData.minimumBalance}`;
-    
-    query += `&merchantReference=${establishData.merchantReference}`;
-    query += `&paymentType=${establishData.paymentType}`;
-    
-    if (establishData.timeZone) query += `&timeZone=${establishData.timeZone}`;
+export const createSignatureQueryString = (establishData: EstablishDto) => {
+  const searchParams: string[] = [];
 
-    if (establishData.paymentType === 'Recurring' && establishData.recurrence) {
-        if (establishData.recurrence.startDate) query += `&recurrence.startDate=${establishData.recurrence.startDate}`;
-        if (establishData.recurrence.endDate) query += `&recurrence.endDate=${establishData.recurrence.endDate}`;
-        if (establishData.recurrence.frequency) query += `&recurrence.frequency=${establishData.recurrence.frequency}`;
-        if (establishData.recurrence.frequencyUnit) query += `&recurrence.frequencyUnit=${establishData.recurrence.frequencyUnit}`;
-        if (establishData.recurrence.frequencyUnitType) query += `&recurrence.frequencyUnitType=${establishData.recurrence.frequencyUnitType}`;
-        if (establishData.recurrence.recurringAmount) query += `&recurrence.recurringAmount=${establishData.recurrence.recurringAmount}`;
-        if (establishData.recurrence.automaticCapture) query += `&recurrence.automaticCapture=${establishData.recurrence.automaticCapture}`;
-    }
+  const appendSearchParam = (key: string, value: any) => {
+    value && searchParams.push(`${key}=${value.toString()}`);
+  };
 
-    if (establishData.verification) {
-        if (establishData.verification.status) query += `&verification.status=${establishData.verification.status}`;
-        if (establishData.verification.verifyCustomer) query += `&verification.verifyCustomer=${establishData.verification.verifyCustomer}`;
+  for (const key of signatureKeysOrdered) {
+    if (!key.includes('.')) {
+      appendSearchParam(key, establishData[key]);
+      continue;
     }
 
-    if (establishData.customer) {
-        if (establishData.customer.customerId) query += `&customer.customerId=${establishData.customer.customerId}`;
-        if (establishData.customer.externalId) query += `&customer.externalId=${establishData.customer.externalId}`;
-        if (establishData.customer.name) query += `&customer.name=${establishData.customer.name}`;
-        if (establishData.customer.vip !== undefined) query += `&customer.vip=${establishData.customer.vip}`;
-        if (establishData.customer.taxId) query += `&customer.taxId=${establishData.customer.taxId}`;
-        if (establishData.customer.driverLicense) {
-            if (establishData.customer.driverLicense.number) query += `&customer.driverLicense.number=${establishData.customer.driverLicense.number}`;
-            if (establishData.customer.driverLicense.state) query += `&customer.driverLicense.state=${establishData.customer.driverLicense.state}`;
-        }
-        if (establishData.customer.address) {
-            if (establishData.customer.address.address1) query += `&customer.address.address1=${establishData.customer.address.address1}`;
-            if (establishData.customer.address.address2) query += `&customer.address.address2=${establishData.customer.address.address2}`;
-            if (establishData.customer.address.city) query += `&customer.address.city=${establishData.customer.address.city}`;
-            if (establishData.customer.address.state) query += `&customer.address.state=${establishData.customer.address.state}`;
-            if (establishData.customer.address.zip) query += `&customer.address.zip=${establishData.customer.address.zip}`;
-            if (establishData.customer.address.country) query += `&customer.address.country=${establishData.customer.address.country}`;
-        }
-        if (establishData.customer.phone) query += `&customer.phone=${establishData.customer.phone}`;
-        if (establishData.customer.email) query += `&customer.email=${establishData.customer.email}`;
-        if (establishData.customer.balance) query += `&customer.balance=${establishData.customer.balance}`;
-        if (establishData.customer.currency) query += `&customer.currency=${establishData.customer.currency}`;
-        if (establishData.customer.enrollDate) query += `&customer.enrollDate=${establishData.customer.enrollDate}`;
-        if (establishData.customer.dateOfBirth) query += `&customer.dateOfBirth=${establishData.customer.dateOfBirth}`;
-    }
+    const subKeys = key.split('.');
+    let data: EstablishDto = establishData;
+
+    for (const subKey of subKeys) {
+      const innerValue = data[subKey];
 
-    if (establishData.account) {
-        if (establishData.account.nameOnAccount) query += `&account.nameOnAccount=${establishData.account.nameOnAccount}`;
-        if (establishData.account.name) query += `&account.name=${establishData.account.name}`;
-        if (establishData.account.type) query += `&account.type=${establishData.account.type}`;
-        if (establishData.account.profile) query += `&account.profile=${establishData.account.profile}`;
-        if (establishData.account.accountNumber) query += `&account.accountNumber=${establishData.account.accountNumber}`;
-        if (establishData.account.routingNumber) query += `&account.routingNumber=${establishData.account.routingNumber}`;
+      if (typeof innerValue === 'object') {
+        data = innerValue as EstablishDto;
+      } else {
+        appendSearchParam(key, innerValue);
+        break;
+      }
     }
+  }
+
+  return searchParams.join('&');
+};
 
-    if (establishData.transactionId) query += `&transactionId=${establishData.transactionId}`;
+export const generateSignature = (establishData: EstablishDto, accessKey: string) => {
+  const query = createSignatureQueryString(establishData);
+  const requestSignature = crypto.createHmac('sha1', accessKey).update(query).digest('base64');
 
-    const requestSignature = CryptoSignature.createHmac('sha1', accessKey).update(query).digest('base64');
-    return requestSignature;
+  return requestSignature;
 };
 
-export const normalizeEstablishData = (
-  establish: EstablishDto,
-  rawBody: Buffer
-) => {
+export const normalizeEstablishData = (establish: EstablishDto, rawBody: Buffer) => {
   // Remove dot notations
   for (const key in establish) {
     if (key.includes('.')) delete establish[key];
diff --git a/src/main.ts b/src/main.ts
index 07e95da..2e85c11 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -10,7 +10,7 @@ async function bootstrap() {
   });
 
   const config = new DocumentBuilder()
-    .setTitle('Alpha Merchante Backend Demonstration ')
+    .setTitle('Alpha Merchant Backend Demonstration ')
     .setDescription('Simple backend demonstrate how to integrate with Trustly')
     .setVersion('1.0')
     .build();