diff --git a/jest.config.js b/jest.config.js
index 0387f86d..1460edba 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -3,10 +3,10 @@ module.exports = {
   collectCoverageFrom: [
     'src/**/*.{js,jsx,ts,tsx}',
     '!src/registerServiceWorker.js',
-    '!src/index.js',
-    '!src/reducers/index.js',
-    '!src/**/provideServices.js',
-    '!src/container/*.js',
+    '!src/index.ts',
+    '!src/reducers/index.ts',
+    '!src/**/provideServices.ts',
+    '!src/container/*.ts',
   ],
   resolver: 'jest-pnp-resolver',
   setupFiles: [
diff --git a/shlink-web-client.d.ts b/shlink-web-client.d.ts
index 52526860..06f04f6c 100644
--- a/shlink-web-client.d.ts
+++ b/shlink-web-client.d.ts
@@ -1,7 +1,5 @@
-export declare global {
-  declare module '*.png'
-
-  interface Window {
-    __REDUX_DEVTOOLS_EXTENSION_COMPOSE__?: Function;
-  }
+declare module 'event-source-polyfill' {
+  export const EventSourcePolyfill: any;
 }
+
+declare module '*.png'
diff --git a/src/container/store.ts b/src/container/store.ts
index 70ea604e..3196d6c2 100644
--- a/src/container/store.ts
+++ b/src/container/store.ts
@@ -4,7 +4,7 @@ import { save, load, RLSOptions } from 'redux-localstorage-simple';
 import reducers from '../reducers';
 
 const isProduction = process.env.NODE_ENV !== 'production';
-const composeEnhancers: Function = !isProduction && window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__ || compose;
+const composeEnhancers: Function = !isProduction && (window as any).__REDUX_DEVTOOLS_EXTENSION_COMPOSE__ || compose;
 
 const localStorageConfig: RLSOptions = {
   states: [ 'settings', 'servers' ],
diff --git a/src/mercure/helpers/index.js b/src/mercure/helpers/index.js
deleted file mode 100644
index ac824cc5..00000000
--- a/src/mercure/helpers/index.js
+++ /dev/null
@@ -1,28 +0,0 @@
-import { useEffect } from 'react';
-import { EventSourcePolyfill as EventSource } from 'event-source-polyfill';
-
-export const bindToMercureTopic = (mercureInfo, topic, onMessage, onTokenExpired) => () => {
-  const { mercureHubUrl, token, loading, error } = mercureInfo;
-
-  if (loading || error) {
-    return undefined;
-  }
-
-  const hubUrl = new URL(mercureHubUrl);
-
-  hubUrl.searchParams.append('topic', topic);
-  const es = new EventSource(hubUrl, {
-    headers: {
-      Authorization: `Bearer ${token}`,
-    },
-  });
-
-  es.onmessage = ({ data }) => onMessage(JSON.parse(data));
-  es.onerror = ({ status }) => status === 401 && onTokenExpired();
-
-  return () => es.close();
-};
-
-export const useMercureTopicBinding = (mercureInfo, topic, onMessage, onTokenExpired) => {
-  useEffect(bindToMercureTopic(mercureInfo, topic, onMessage, onTokenExpired), [ mercureInfo ]);
-};
diff --git a/src/mercure/helpers/index.ts b/src/mercure/helpers/index.ts
new file mode 100644
index 00000000..8f6eec78
--- /dev/null
+++ b/src/mercure/helpers/index.ts
@@ -0,0 +1,34 @@
+import { useEffect } from 'react';
+import { EventSourcePolyfill as EventSource } from 'event-source-polyfill';
+import { MercureInfo } from '../reducers/mercureInfo';
+
+export const bindToMercureTopic = <T>(mercureInfo: MercureInfo, topic: string, onMessage: (message: T) => void, onTokenExpired: Function) => () => { // eslint-disable-line max-len
+  const { mercureHubUrl, token, loading, error } = mercureInfo;
+
+  if (loading || error || !mercureHubUrl) {
+    return undefined;
+  }
+
+  const hubUrl = new URL(mercureHubUrl);
+
+  hubUrl.searchParams.append('topic', topic);
+  const es = new EventSource(hubUrl, {
+    headers: {
+      Authorization: `Bearer ${token}`,
+    },
+  });
+
+  es.onmessage = ({ data }: { data: string }) => onMessage(JSON.parse(data) as T);
+  es.onerror = ({ status }: { status: number }) => status === 401 && onTokenExpired();
+
+  return () => es.close();
+};
+
+export const useMercureTopicBinding = <T>(
+  mercureInfo: MercureInfo,
+  topic: string,
+  onMessage: (message: T) => void,
+  onTokenExpired: Function,
+) => {
+  useEffect(bindToMercureTopic(mercureInfo, topic, onMessage, onTokenExpired), [ mercureInfo ]);
+};
diff --git a/src/servers/helpers/ForServerVersion.js b/src/servers/helpers/ForServerVersion.js
deleted file mode 100644
index 0b3c6fba..00000000
--- a/src/servers/helpers/ForServerVersion.js
+++ /dev/null
@@ -1,30 +0,0 @@
-import React from 'react';
-import PropTypes from 'prop-types';
-import { serverType } from '../prop-types';
-import { versionMatch } from '../../utils/helpers/version';
-
-const propTypes = {
-  minVersion: PropTypes.string,
-  maxVersion: PropTypes.string,
-  selectedServer: serverType,
-  children: PropTypes.node.isRequired,
-};
-
-const ForServerVersion = ({ minVersion, maxVersion, selectedServer, children }) => {
-  if (!selectedServer) {
-    return null;
-  }
-
-  const { version } = selectedServer;
-  const matchesVersion = versionMatch(version, { maxVersion, minVersion });
-
-  if (!matchesVersion) {
-    return null;
-  }
-
-  return <React.Fragment>{children}</React.Fragment>;
-};
-
-ForServerVersion.propTypes = propTypes;
-
-export default ForServerVersion;
diff --git a/src/servers/helpers/ForServerVersion.tsx b/src/servers/helpers/ForServerVersion.tsx
new file mode 100644
index 00000000..3fe61e1a
--- /dev/null
+++ b/src/servers/helpers/ForServerVersion.tsx
@@ -0,0 +1,24 @@
+import React, { FC } from 'react';
+import { versionMatch, Versions } from '../../utils/helpers/version';
+import { isReachableServer, SelectedServer } from '../data';
+
+interface ForServerVersionProps extends Versions {
+  selectedServer: SelectedServer;
+}
+
+const ForServerVersion: FC<ForServerVersionProps> = ({ minVersion, maxVersion, selectedServer, children }) => {
+  if (!isReachableServer(selectedServer)) {
+    return null;
+  }
+
+  const { version } = selectedServer;
+  const matchesVersion = versionMatch(version, { maxVersion, minVersion });
+
+  if (!matchesVersion) {
+    return null;
+  }
+
+  return <React.Fragment>{children}</React.Fragment>;
+};
+
+export default ForServerVersion;
diff --git a/src/servers/helpers/ServerForm.js b/src/servers/helpers/ServerForm.tsx
similarity index 67%
rename from src/servers/helpers/ServerForm.js
rename to src/servers/helpers/ServerForm.tsx
index 03c60868..cf9afa1f 100644
--- a/src/servers/helpers/ServerForm.js
+++ b/src/servers/helpers/ServerForm.tsx
@@ -1,19 +1,14 @@
-import React, { useEffect, useState } from 'react';
-import PropTypes from 'prop-types';
+import React, { FC, useEffect, useState } from 'react';
 import { HorizontalFormGroup } from '../../utils/HorizontalFormGroup';
 import { handleEventPreventingDefault } from '../../utils/utils';
+import { ServerData } from '../data';
 
-const propTypes = {
-  onSubmit: PropTypes.func.isRequired,
-  initialValues: PropTypes.shape({
-    name: PropTypes.string.isRequired,
-    url: PropTypes.string.isRequired,
-    apiKey: PropTypes.string.isRequired,
-  }),
-  children: PropTypes.node.isRequired,
-};
+interface ServerFormProps {
+  onSubmit: (server: ServerData) => void;
+  initialValues?: ServerData;
+}
 
-export const ServerForm = ({ onSubmit, initialValues, children }) => {
+export const ServerForm: FC<ServerFormProps> = ({ onSubmit, initialValues, children }) => {
   const [ name, setName ] = useState('');
   const [ url, setUrl ] = useState('');
   const [ apiKey, setApiKey ] = useState('');
@@ -35,5 +30,3 @@ export const ServerForm = ({ onSubmit, initialValues, children }) => {
     </form>
   );
 };
-
-ServerForm.propTypes = propTypes;
diff --git a/src/servers/helpers/withSelectedServer.js b/src/servers/helpers/withSelectedServer.js
deleted file mode 100644
index 737f9894..00000000
--- a/src/servers/helpers/withSelectedServer.js
+++ /dev/null
@@ -1,35 +0,0 @@
-import React, { useEffect } from 'react';
-import PropTypes from 'prop-types';
-import Message from '../../utils/Message';
-import { serverType } from '../prop-types';
-
-const propTypes = {
-  selectServer: PropTypes.func,
-  selectedServer: serverType,
-  match: PropTypes.object,
-};
-
-export const withSelectedServer = (WrappedComponent, ServerError) => {
-  const Component = (props) => {
-    const { selectServer, selectedServer, match } = props;
-    const { params: { serverId } } = match;
-
-    useEffect(() => {
-      selectServer(serverId);
-    }, [ serverId ]);
-
-    if (!selectedServer) {
-      return <Message loading />;
-    }
-
-    if (selectedServer.serverNotFound) {
-      return <ServerError />;
-    }
-
-    return <WrappedComponent {...props} />;
-  };
-
-  Component.propTypes = propTypes;
-
-  return Component;
-};
diff --git a/src/servers/helpers/withSelectedServer.tsx b/src/servers/helpers/withSelectedServer.tsx
new file mode 100644
index 00000000..2215ded3
--- /dev/null
+++ b/src/servers/helpers/withSelectedServer.tsx
@@ -0,0 +1,29 @@
+import React, { FC, useEffect } from 'react';
+import { RouteChildrenProps } from 'react-router';
+import Message from '../../utils/Message';
+import { isReachableServer, SelectedServer } from '../data';
+
+interface WithSelectedServerProps extends RouteChildrenProps<{ serverId: string }> {
+  selectServer: (serverId: string) => void;
+  selectedServer: SelectedServer;
+}
+
+export const withSelectedServer = (WrappedComponent: FC<WithSelectedServerProps>, ServerError: FC) => (
+  props: WithSelectedServerProps,
+) => {
+  const { selectServer, selectedServer, match } = props;
+
+  useEffect(() => {
+    match?.params?.serverId && selectServer(match?.params.serverId);
+  }, [ match?.params.serverId ]);
+
+  if (!selectedServer) {
+    return <Message loading />;
+  }
+
+  if (!isReachableServer(selectedServer)) {
+    return <ServerError />;
+  }
+
+  return <WrappedComponent {...props} />;
+};
diff --git a/test/mercure/helpers/index.test.js b/test/mercure/helpers/index.test.tsx
similarity index 65%
rename from test/mercure/helpers/index.test.js
rename to test/mercure/helpers/index.test.tsx
index 1e6fd3df..3a7f897f 100644
--- a/test/mercure/helpers/index.test.js
+++ b/test/mercure/helpers/index.test.tsx
@@ -1,5 +1,8 @@
 import { EventSourcePolyfill as EventSource } from 'event-source-polyfill';
+import { Mock } from 'ts-mockery';
+import { identity } from 'ramda';
 import { bindToMercureTopic } from '../../../src/mercure/helpers';
+import { MercureInfo } from '../../../src/mercure/reducers/mercureInfo';
 
 jest.mock('event-source-polyfill');
 
@@ -11,11 +14,13 @@ describe('helpers', () => {
     const onTokenExpired = jest.fn();
 
     it.each([
-      [{ loading: true, error: false }],
-      [{ loading: false, error: true }],
-      [{ loading: true, error: true }],
-    ])('does not bind an EventSource when loading or error', (mercureInfo) => {
-      bindToMercureTopic(mercureInfo)();
+      [ Mock.of<MercureInfo>({ loading: true, error: false, mercureHubUrl: 'foo' }) ],
+      [ Mock.of<MercureInfo>({ loading: false, error: true, mercureHubUrl: 'foo' }) ],
+      [ Mock.of<MercureInfo>({ loading: true, error: true, mercureHubUrl: 'foo' }) ],
+      [ Mock.of<MercureInfo>({ loading: false, error: false, mercureHubUrl: undefined }) ],
+      [ Mock.of<MercureInfo>({ loading: true, error: true, mercureHubUrl: undefined }) ],
+    ])('does not bind an EventSource when loading, error or no hub URL', (mercureInfo) => {
+      bindToMercureTopic(mercureInfo, '', identity, identity)();
 
       expect(EventSource).not.toHaveBeenCalled();
       expect(onMessage).not.toHaveBeenCalled();
@@ -50,7 +55,7 @@ describe('helpers', () => {
       expect(onMessage).toHaveBeenCalledWith({ foo: 'bar' });
       expect(onTokenExpired).toHaveBeenCalled();
 
-      callback();
+      callback?.();
       expect(es.close).toHaveBeenCalled();
     });
   });
diff --git a/test/servers/EditServer.test.js b/test/servers/EditServer.test.js
index 366dd24f..0dd0f155 100644
--- a/test/servers/EditServer.test.js
+++ b/test/servers/EditServer.test.js
@@ -16,6 +16,8 @@ describe('<EditServer />', () => {
     name: 'name',
     url: 'url',
     apiKey: 'apiKey',
+    printableVersion: 'v1.2.0',
+    version: '1.2.0'
   };
 
   beforeEach(() => {
diff --git a/test/servers/helpers/ForServerVersion.test.js b/test/servers/helpers/ForServerVersion.test.tsx
similarity index 64%
rename from test/servers/helpers/ForServerVersion.test.js
rename to test/servers/helpers/ForServerVersion.test.tsx
index 171d2feb..daaadc24 100644
--- a/test/servers/helpers/ForServerVersion.test.js
+++ b/test/servers/helpers/ForServerVersion.test.tsx
@@ -1,11 +1,13 @@
 import React from 'react';
-import { mount } from 'enzyme';
+import { mount, ReactWrapper } from 'enzyme';
+import { Mock } from 'ts-mockery';
 import ForServerVersion from '../../../src/servers/helpers/ForServerVersion';
+import { ReachableServer, SelectedServer } from '../../../src/servers/data';
 
 describe('<ForServerVersion />', () => {
-  let wrapped;
+  let wrapped: ReactWrapper;
 
-  const renderComponent = (minVersion, maxVersion, selectedServer) => {
+  const renderComponent = (selectedServer: SelectedServer, minVersion?: string, maxVersion?: string) => {
     wrapped = mount(
       <ForServerVersion minVersion={minVersion} maxVersion={maxVersion} selectedServer={selectedServer}>
         <span>Hello</span>
@@ -15,10 +17,10 @@ describe('<ForServerVersion />', () => {
     return wrapped;
   };
 
-  afterEach(() => wrapped && wrapped.unmount());
+  afterEach(() => wrapped?.unmount());
 
   it('does not render children when current server is empty', () => {
-    const wrapped = renderComponent('1');
+    const wrapped = renderComponent(null, '1');
 
     expect(wrapped.html()).toBeNull();
   });
@@ -28,7 +30,7 @@ describe('<ForServerVersion />', () => {
     [ undefined, '1.8.0', '1.8.3' ],
     [ '1.7.0', '1.8.0', '1.8.3' ],
   ])('does not render children when current version does not match requirements', (min, max, version) => {
-    const wrapped = renderComponent(min, max, { version });
+    const wrapped = renderComponent(Mock.of<ReachableServer>({ version, printableVersion: version }), min, max);
 
     expect(wrapped.html()).toBeNull();
   });
@@ -40,7 +42,7 @@ describe('<ForServerVersion />', () => {
     [ undefined, '1.8.0', '1.7.1' ],
     [ '1.7.0', '1.8.0', '1.7.3' ],
   ])('renders children when current version matches requirements', (min, max, version) => {
-    const wrapped = renderComponent(min, max, { version });
+    const wrapped = renderComponent(Mock.of<ReachableServer>({ version, printableVersion: version }), min, max);
 
     expect(wrapped.html()).toContain('<span>Hello</span>');
   });
diff --git a/test/servers/helpers/ServerForm.test.js b/test/servers/helpers/ServerForm.test.tsx
similarity index 84%
rename from test/servers/helpers/ServerForm.test.js
rename to test/servers/helpers/ServerForm.test.tsx
index 855e8c1e..52020f5c 100644
--- a/test/servers/helpers/ServerForm.test.js
+++ b/test/servers/helpers/ServerForm.test.tsx
@@ -1,20 +1,18 @@
 import React from 'react';
-import { shallow } from 'enzyme';
+import { shallow, ShallowWrapper } from 'enzyme';
 import { ServerForm } from '../../../src/servers/helpers/ServerForm';
 import { HorizontalFormGroup } from '../../../src/utils/HorizontalFormGroup';
 
 describe('<ServerForm />', () => {
-  let wrapper;
+  let wrapper: ShallowWrapper;
   const onSubmit = jest.fn();
 
   beforeEach(() => {
     wrapper = shallow(<ServerForm onSubmit={onSubmit}><span>Something</span></ServerForm>);
   });
 
-  afterEach(() => {
-    jest.resetAllMocks();
-    wrapper && wrapper.unmount();
-  });
+  afterEach(() => wrapper?.unmount());
+  afterEach(jest.resetAllMocks);
 
   it('renders components', () => {
     expect(wrapper.find(HorizontalFormGroup)).toHaveLength(3);