diff --git a/src/utils/BooleanControl.js b/src/utils/BooleanControl.tsx
similarity index 50%
rename from src/utils/BooleanControl.js
rename to src/utils/BooleanControl.tsx
index 3daa7d9f..acf46c93 100644
--- a/src/utils/BooleanControl.js
+++ b/src/utils/BooleanControl.tsx
@@ -1,23 +1,23 @@
-import React from 'react';
-import PropTypes from 'prop-types';
+import React, { ChangeEvent, FC } from 'react';
 import classNames from 'classnames';
 import { v4 as uuid } from 'uuid';
+import { identity } from 'ramda';
 
-export const basePropTypes = {
-  checked: PropTypes.bool.isRequired,
-  onChange: PropTypes.func.isRequired,
-  children: PropTypes.oneOfType([ PropTypes.string, PropTypes.node ]),
-  className: PropTypes.string,
-};
+export interface BooleanControlProps {
+  checked?: boolean;
+  onChange?: (checked: boolean, e: ChangeEvent<HTMLInputElement>) => void;
+  className?: string;
+}
 
-const propTypes = {
-  ...basePropTypes,
-  type: PropTypes.oneOf([ 'switch', 'checkbox' ]).isRequired,
-};
+interface BooleanControlWithTypeProps extends BooleanControlProps {
+  type: 'switch' | 'checkbox';
+}
 
-const BooleanControl = ({ checked, onChange, className, children, type }) => {
+const BooleanControl: FC<BooleanControlWithTypeProps> = (
+  { checked = false, onChange = identity, className, children, type },
+) => {
   const id = uuid();
-  const onChecked = (e) => onChange(e.target.checked, e);
+  const onChecked = (e: ChangeEvent<HTMLInputElement>) => onChange(e.target.checked, e);
   const typeClasses = {
     'custom-switch': type === 'switch',
     'custom-checkbox': type === 'checkbox',
@@ -31,6 +31,4 @@ const BooleanControl = ({ checked, onChange, className, children, type }) => {
   );
 };
 
-BooleanControl.propTypes = propTypes;
-
 export default BooleanControl;
diff --git a/src/utils/Checkbox.js b/src/utils/Checkbox.js
deleted file mode 100644
index b253bdfc..00000000
--- a/src/utils/Checkbox.js
+++ /dev/null
@@ -1,8 +0,0 @@
-import React from 'react';
-import BooleanControl, { basePropTypes } from './BooleanControl';
-
-const Checkbox = (props) => <BooleanControl type="checkbox" {...props} />;
-
-Checkbox.propTypes = basePropTypes;
-
-export default Checkbox;
diff --git a/src/utils/Checkbox.tsx b/src/utils/Checkbox.tsx
new file mode 100644
index 00000000..56bc1181
--- /dev/null
+++ b/src/utils/Checkbox.tsx
@@ -0,0 +1,6 @@
+import React, { FC } from 'react';
+import BooleanControl, { BooleanControlProps } from './BooleanControl';
+
+const Checkbox: FC<BooleanControlProps> = (props) => <BooleanControl type="checkbox" {...props} />;
+
+export default Checkbox;
diff --git a/src/utils/ToggleSwitch.js b/src/utils/ToggleSwitch.js
deleted file mode 100644
index 8f45e96f..00000000
--- a/src/utils/ToggleSwitch.js
+++ /dev/null
@@ -1,8 +0,0 @@
-import React from 'react';
-import BooleanControl, { basePropTypes } from './BooleanControl';
-
-const ToggleSwitch = (props) => <BooleanControl type="switch" {...props} />;
-
-ToggleSwitch.propTypes = basePropTypes;
-
-export default ToggleSwitch;
diff --git a/src/utils/ToggleSwitch.tsx b/src/utils/ToggleSwitch.tsx
new file mode 100644
index 00000000..3427b143
--- /dev/null
+++ b/src/utils/ToggleSwitch.tsx
@@ -0,0 +1,6 @@
+import React, { FC } from 'react';
+import BooleanControl, { BooleanControlProps } from './BooleanControl';
+
+const ToggleSwitch: FC<BooleanControlProps> = (props) => <BooleanControl type="switch" {...props} />;
+
+export default ToggleSwitch;
diff --git a/src/utils/helpers/visits.js b/src/utils/helpers/visits.ts
similarity index 59%
rename from src/utils/helpers/visits.js
rename to src/utils/helpers/visits.ts
index 51d898f4..4bd0ab49 100644
--- a/src/utils/helpers/visits.js
+++ b/src/utils/helpers/visits.ts
@@ -1,6 +1,6 @@
 import bowser from 'bowser';
 import { zipObj } from 'ramda';
-import { hasValue } from '../utils';
+import { Empty, hasValue } from '../utils';
 
 const DEFAULT = 'Others';
 const BROWSERS_WHITELIST = [
@@ -17,17 +17,22 @@ const BROWSERS_WHITELIST = [
   'WeChat',
 ];
 
-export const parseUserAgent = (userAgent) => {
+interface UserAgent {
+  browser: string;
+  os: string;
+}
+
+export const parseUserAgent = (userAgent: string | Empty): UserAgent => {
   if (!hasValue(userAgent)) {
     return { browser: DEFAULT, os: DEFAULT };
   }
 
   const { browser: { name: browser }, os: { name: os } } = bowser.parse(userAgent);
 
-  return { os: os || DEFAULT, browser: browser && BROWSERS_WHITELIST.includes(browser) ? browser : DEFAULT };
+  return { os: os ?? DEFAULT, browser: browser && BROWSERS_WHITELIST.includes(browser) ? browser : DEFAULT };
 };
 
-export const extractDomain = (url) => {
+export const extractDomain = (url: string | Empty): string => {
   if (!hasValue(url)) {
     return 'Direct';
   }
@@ -37,4 +42,5 @@ export const extractDomain = (url) => {
   return domain.split(':')[0];
 };
 
-export const fillTheGaps = (stats, labels) => Object.values({ ...zipObj(labels, labels.map(() => 0)), ...stats });
+export const fillTheGaps = (stats: Record<string, number>, labels: string[]): number[] =>
+  Object.values({ ...zipObj(labels, labels.map(() => 0)), ...stats });
diff --git a/src/utils/utils.ts b/src/utils/utils.ts
index 3fc26d0f..27521f1e 100644
--- a/src/utils/utils.ts
+++ b/src/utils/utils.ts
@@ -2,7 +2,7 @@ import { isEmpty, isNil, range } from 'ramda';
 
 export type OrderDir = 'ASC' | 'DESC' | undefined;
 
-export const determineOrderDir = (currentField: string, newField: string, currentOrderDir: OrderDir): OrderDir => {
+export const determineOrderDir = (currentField: string, newField: string, currentOrderDir?: OrderDir): OrderDir => {
   if (currentField !== newField) {
     return 'ASC';
   }
diff --git a/test/utils/Checkbox.test.js b/test/utils/Checkbox.test.tsx
similarity index 76%
rename from test/utils/Checkbox.test.js
rename to test/utils/Checkbox.test.tsx
index 78c8afec..b923e3f8 100644
--- a/test/utils/Checkbox.test.js
+++ b/test/utils/Checkbox.test.tsx
@@ -1,17 +1,19 @@
-import React from 'react';
-import { mount } from 'enzyme';
+import React, { ChangeEvent, PropsWithChildren } from 'react';
+import { mount, ReactWrapper } from 'enzyme';
+import { Mock } from 'ts-mockery';
 import Checkbox from '../../src/utils/Checkbox';
+import { BooleanControlProps } from '../../src/utils/BooleanControl';
 
 describe('<Checkbox />', () => {
-  let wrapped;
+  let wrapped: ReactWrapper;
 
-  const createComponent = (props = {}) => {
+  const createComponent = (props: PropsWithChildren<BooleanControlProps> = {}) => {
     wrapped = mount(<Checkbox {...props} />);
 
     return wrapped;
   };
 
-  afterEach(() => wrapped && wrapped.unmount());
+  afterEach(() => wrapped?.unmount());
 
   it('includes extra class names when provided', () => {
     const classNames = [ 'foo', 'bar', 'baz' ];
@@ -55,11 +57,11 @@ describe('<Checkbox />', () => {
 
   it('changes checked status on input change', () => {
     const onChange = jest.fn();
-    const e = { target: { checked: false } };
+    const e = Mock.of<ChangeEvent<HTMLInputElement>>({ target: { checked: false } });
     const wrapped = createComponent({ checked: true, onChange });
     const input = wrapped.find('input');
 
-    input.prop('onChange')(e);
+    (input.prop('onChange') as Function)(e);
 
     expect(onChange).toHaveBeenCalledWith(false, e);
   });
diff --git a/test/utils/utils.test.js b/test/utils/utils.test.ts
similarity index 100%
rename from test/utils/utils.test.js
rename to test/utils/utils.test.ts