diff --git a/src/utils/api-requests/summary.requests.js b/src/utils/api-requests/summary.requests.ts
similarity index 100%
rename from src/utils/api-requests/summary.requests.js
rename to src/utils/api-requests/summary.requests.ts
diff --git a/src/utils/api-requests/useful-tools.requests.js b/src/utils/api-requests/useful-tools.requests.ts
similarity index 77%
rename from src/utils/api-requests/useful-tools.requests.js
rename to src/utils/api-requests/useful-tools.requests.ts
index 317bc67..2899bcb 100644
--- a/src/utils/api-requests/useful-tools.requests.js
+++ b/src/utils/api-requests/useful-tools.requests.ts
@@ -1,7 +1,8 @@
+import { CurrencyConversionInput, ExchangeRateInput, MortgageInput } from "../../contexts/shared/useful-tools/useful-tools.types";
 import { errorOnMortgageResult, errorOnCurrencyResult } from "../errors/useful-tools.errors";
 
 // mortgage calculator
-export async function getMortgageResult(mortgageInput) {
+export async function getMortgageResult(mortgageInput: MortgageInput): Promise<any> {
   try {
     
     const response = await fetch(`${process.env.REACT_APP_API_URL_USEFUL_TOOLS}${process.env.REACT_APP_API_URL_USEFUL_TOOLS_MORTGAGE_CALCULATOR}`, {
@@ -22,7 +23,7 @@ export async function getMortgageResult(mortgageInput) {
 
 // currency converter
 // exchange rate
-export async function getExchangeRate(currencyInput) {
+export async function getExchangeRate(currencyInput: ExchangeRateInput): Promise<any> {
   try {
     
     const response = await fetch(`${process.env.REACT_APP_API_URL_USEFUL_TOOLS}${process.env.REACT_APP_API_URL_USEFUL_TOOLS_EXCHANGE_RATE}`, {
diff --git a/src/utils/calculations/useful-tools.calculations.js b/src/utils/calculations/useful-tools.calculations.ts
similarity index 100%
rename from src/utils/calculations/useful-tools.calculations.js
rename to src/utils/calculations/useful-tools.calculations.ts
diff --git a/src/utils/constants/shared.constants.js b/src/utils/constants/shared.constants.ts
similarity index 100%
rename from src/utils/constants/shared.constants.js
rename to src/utils/constants/shared.constants.ts
diff --git a/src/utils/constants/useful-tools.constants.js b/src/utils/constants/useful-tools.constants.js
deleted file mode 100644
index ddb3181..0000000
--- a/src/utils/constants/useful-tools.constants.js
+++ /dev/null
@@ -1,6 +0,0 @@
-// useful tools constants
-
-export const DOWNPAYMENT_FLAG_OPTIONS = {
-  yes: "Yes",
-  no: "No"
-}
\ No newline at end of file
diff --git a/src/utils/constants/useful-tools.constants.ts b/src/utils/constants/useful-tools.constants.ts
new file mode 100644
index 0000000..e2dae20
--- /dev/null
+++ b/src/utils/constants/useful-tools.constants.ts
@@ -0,0 +1,6 @@
+// useful tools constants
+
+export enum DOWNPAYMENT_FLAG_OPTIONS {
+  yes = "Yes",
+  no = "No"
+}
\ No newline at end of file
diff --git a/src/utils/errors/summary.errors.js b/src/utils/errors/summary.errors.ts
similarity index 100%
rename from src/utils/errors/summary.errors.js
rename to src/utils/errors/summary.errors.ts
diff --git a/src/utils/errors/useful-tools.errors.js b/src/utils/errors/useful-tools.errors.ts
similarity index 100%
rename from src/utils/errors/useful-tools.errors.js
rename to src/utils/errors/useful-tools.errors.ts
diff --git a/src/utils/errors/user.errors.js b/src/utils/errors/user.errors.ts
similarity index 60%
rename from src/utils/errors/user.errors.js
rename to src/utils/errors/user.errors.ts
index 7ceb1bc..f7e696e 100644
--- a/src/utils/errors/user.errors.js
+++ b/src/utils/errors/user.errors.ts
@@ -1,10 +1,10 @@
 // user errors
 
-export const errorOnCreatingUser = (error) => {
+export const errorOnCreatingUser = (error: Error) => {
   alert(`Error creating the user ${error.message}`)
 };
 
-export const errorOnUserSignIn = (error) => {
+export const errorOnUserSignIn = (error: Error) => {
   alert(`Error signing in ${error.message}`);
 };
 
@@ -12,6 +12,6 @@ export const errorOnEmailAlreadyInUse = () => {
   alert(`Email already in use`);
 };
 
-export const errorOnUserCreation = (error) => {
+export const errorOnUserCreation = (error: Error) => {
   alert(`User creation ${error.message}`);
 };
diff --git a/src/utils/firebase/firebase.utils.ts b/src/utils/firebase/firebase.utils.ts
index 6562319..a0283e4 100644
--- a/src/utils/firebase/firebase.utils.ts
+++ b/src/utils/firebase/firebase.utils.ts
@@ -127,7 +127,7 @@ export const createUserDocumentFromAuth = async (
         ...additionalInformation,
       });
     } catch (error) {
-      errorOnCreatingUser(error);
+      errorOnCreatingUser(error as Error);
     }
   }
 
diff --git a/src/utils/validations/useful-tools.validation.js b/src/utils/validations/useful-tools.validation.ts
similarity index 69%
rename from src/utils/validations/useful-tools.validation.js
rename to src/utils/validations/useful-tools.validation.ts
index 2398791..b363166 100644
--- a/src/utils/validations/useful-tools.validation.js
+++ b/src/utils/validations/useful-tools.validation.ts
@@ -4,11 +4,12 @@ import { errorOnInvalidMortgageInput,
 
 import { DOWNPAYMENT_FLAG_OPTIONS } from "../constants/useful-tools.constants";
 import { REGEX_PATTERNS } from "../constants/regex.constants";
+import { CurrencyConversionInput, ExchangeRateInput, MortgageInput } from "../../contexts/shared/useful-tools/useful-tools.types";
 
 // useful tools validation functions
 
 // mortgage calculator
-export const validateMortgageInput = (mortgageInput) => {
+export const validateMortgageInput = (mortgageInput: MortgageInput): boolean => {
   if (mortgageInput.downpaymentFlag === DOWNPAYMENT_FLAG_OPTIONS.no) {
     if (!(REGEX_PATTERNS.floatNumbers.test(String(mortgageInput.loanAmount))) || Number(mortgageInput.loanAmount) <= 0) {
       errorOnInvalidMortgageInput();
@@ -28,9 +29,9 @@ export const validateMortgageInput = (mortgageInput) => {
       return true;
   }
 
-  if ((mortgageInput.monthlyHoa !== "" && (!(REGEX_PATTERNS.floatNumbers.test(String(mortgageInput.monthlyHoa))) || Number(mortgageInput.monthlyHoa) <= 0)) ||
-    (mortgageInput.annualPropertyTax !== "" && (!(REGEX_PATTERNS.floatNumbers.test(String(mortgageInput.annualPropertyTax))) || Number(mortgageInput.annualPropertyTax) <= 0)) ||
-    (mortgageInput.annualHomeInsurance !== "" && (!(REGEX_PATTERNS.floatNumbers.test(String(mortgageInput.annualHomeInsurance))) || Number(mortgageInput.annualHomeInsurance) <= 0))) {
+  if ((mortgageInput.monthlyHoa && (!(REGEX_PATTERNS.floatNumbers.test(String(mortgageInput.monthlyHoa))) || Number(mortgageInput.monthlyHoa) <= 0)) ||
+    (mortgageInput.annualPropertyTax && (!(REGEX_PATTERNS.floatNumbers.test(String(mortgageInput.annualPropertyTax))) || Number(mortgageInput.annualPropertyTax) <= 0)) ||
+    (mortgageInput.annualHomeInsurance && (!(REGEX_PATTERNS.floatNumbers.test(String(mortgageInput.annualHomeInsurance))) || Number(mortgageInput.annualHomeInsurance) <= 0))) {
     errorOnInvalidMortgageInput();
     return true;
   }
@@ -39,7 +40,7 @@ export const validateMortgageInput = (mortgageInput) => {
 }
 
 // currency converter
-export const validateCurrencyConverterInput = (currencyInput) => {
+export const validateCurrencyConverterInput = (currencyInput: CurrencyConversionInput): boolean => {
   if (!(REGEX_PATTERNS.floatNumbers.test(String(currencyInput.fromCurrencyAmount))) || Number(currencyInput.fromCurrencyAmount) <= 0) {
     errorOnInvalidCurrencyConverterInput()
     return true
@@ -55,7 +56,7 @@ export const validateCurrencyConverterInput = (currencyInput) => {
 }
 
 // exchange rate
-export const validateExchangeRateInput = (currencyInput) => {
+export const validateExchangeRateInput = (currencyInput: ExchangeRateInput): boolean => {
   // strings
   if (!(REGEX_PATTERNS.currency.test(String(currencyInput.fromCurrency))) || !(REGEX_PATTERNS.currency.test(String(currencyInput.toCurrency)))) {
     errorOnInvalidExchangeRateInput();