diff --git a/.eslintignore b/.eslintignore
index 6a8267f9478f..c75dfdc42484 100644
--- a/.eslintignore
+++ b/.eslintignore
@@ -14,6 +14,7 @@ packages/docusaurus/lib/
 packages/docusaurus-*/lib/*
 packages/docusaurus-*/lib-next/
 packages/docusaurus-plugin-ideal-image/copyUntypedFiles.js
+packages/docusaurus-theme-search-algolia/copyUntypedFiles.js
 
 packages/create-docusaurus/lib/*
 packages/create-docusaurus/templates/facebook/.eslintrc.js
diff --git a/packages/docusaurus-plugin-ideal-image/copyUntypedFiles.js b/packages/docusaurus-plugin-ideal-image/copyUntypedFiles.js
index 3f814cf0990d..e5555c55368f 100644
--- a/packages/docusaurus-plugin-ideal-image/copyUntypedFiles.js
+++ b/packages/docusaurus-plugin-ideal-image/copyUntypedFiles.js
@@ -15,6 +15,6 @@ const srcDir = path.resolve(__dirname, 'src');
 const libDir = path.resolve(__dirname, 'lib');
 fs.copySync(srcDir, libDir, {
   filter(filepath) {
-    return !/__tests__/.test(filepath) && !/\.ts$/.test(filepath);
+    return !/__tests__/.test(filepath) && !/\.tsx?$/.test(filepath);
   },
 });
diff --git a/packages/docusaurus-theme-classic/update-code-translations.js b/packages/docusaurus-theme-classic/update-code-translations.js
index 18e570c06d7a..73cba2ff9679 100644
--- a/packages/docusaurus-theme-classic/update-code-translations.js
+++ b/packages/docusaurus-theme-classic/update-code-translations.js
@@ -15,7 +15,7 @@ const CodeDirPaths = [
   path.join(__dirname, 'lib-next'),
   // TODO other themes should rather define their own translations in the future?
   path.join(__dirname, '..', 'docusaurus-theme-common', 'lib'),
-  path.join(__dirname, '..', 'docusaurus-theme-search-algolia', 'src', 'theme'),
+  path.join(__dirname, '..', 'docusaurus-theme-search-algolia', 'lib', 'theme'),
   path.join(__dirname, '..', 'docusaurus-theme-live-codeblock', 'src', 'theme'),
   path.join(__dirname, '..', 'docusaurus-plugin-pwa', 'src', 'theme'),
 ];
diff --git a/packages/docusaurus-theme-common/src/index.ts b/packages/docusaurus-theme-common/src/index.ts
index e1bb425c61f3..0a7890aba957 100644
--- a/packages/docusaurus-theme-common/src/index.ts
+++ b/packages/docusaurus-theme-common/src/index.ts
@@ -22,6 +22,8 @@ export {createStorageSlot, listStorageKeys} from './utils/storageUtils';
 
 export {useAlternatePageUtils} from './utils/useAlternatePageUtils';
 
+export {useContextualSearchFilters} from './utils/useContextualSearchFilters';
+
 export {
   parseCodeBlockTitle,
   parseLanguage,
diff --git a/packages/docusaurus-theme-classic/src/theme/hooks/useContextualSearchFilters.ts b/packages/docusaurus-theme-common/src/utils/useContextualSearchFilters.ts
similarity index 82%
rename from packages/docusaurus-theme-classic/src/theme/hooks/useContextualSearchFilters.ts
rename to packages/docusaurus-theme-common/src/utils/useContextualSearchFilters.ts
index 38e27d2bc0e6..2dd1741d1b8f 100644
--- a/packages/docusaurus-theme-classic/src/theme/hooks/useContextualSearchFilters.ts
+++ b/packages/docusaurus-theme-common/src/utils/useContextualSearchFilters.ts
@@ -5,21 +5,18 @@
  * LICENSE file in the root directory of this source tree.
  */
 import {useAllDocsData, useActivePluginAndVersion} from '@theme/hooks/useDocs';
-import {
-  useDocsPreferredVersionByPluginId,
-  DEFAULT_SEARCH_TAG,
-  docVersionSearchTag,
-} from '@docusaurus/theme-common';
+import {useDocsPreferredVersionByPluginId} from './docsPreferredVersion/useDocsPreferredVersion';
+import {docVersionSearchTag, DEFAULT_SEARCH_TAG} from './searchUtils';
 import useDocusaurusContext from '@docusaurus/useDocusaurusContext';
 
-type ContextualSearchFilters = {
+export type useContextualSearchFiltersReturns = {
   locale: string;
   tags: string[];
 };
 
 // We may want to support multiple search engines, don't couple that to Algolia/DocSearch
 // Maybe users will want to use its own search engine solution
-export default function useContextualSearchFilters(): ContextualSearchFilters {
+export function useContextualSearchFilters(): useContextualSearchFiltersReturns {
   const {i18n} = useDocusaurusContext();
   const allDocsData = useAllDocsData();
   const activePluginAndVersion = useActivePluginAndVersion();
diff --git a/packages/docusaurus-theme-search-algolia/copyUntypedFiles.js b/packages/docusaurus-theme-search-algolia/copyUntypedFiles.js
new file mode 100644
index 000000000000..e5555c55368f
--- /dev/null
+++ b/packages/docusaurus-theme-search-algolia/copyUntypedFiles.js
@@ -0,0 +1,20 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+const path = require('path');
+const fs = require('fs-extra');
+
+/**
+ * Copy all untyped and static assets files to lib.
+ */
+const srcDir = path.resolve(__dirname, 'src');
+const libDir = path.resolve(__dirname, 'lib');
+fs.copySync(srcDir, libDir, {
+  filter(filepath) {
+    return !/__tests__/.test(filepath) && !/\.tsx?$/.test(filepath);
+  },
+});
diff --git a/packages/docusaurus-theme-search-algolia/package.json b/packages/docusaurus-theme-search-algolia/package.json
index 3e64f07c68a4..b7b57443da75 100644
--- a/packages/docusaurus-theme-search-algolia/package.json
+++ b/packages/docusaurus-theme-search-algolia/package.json
@@ -2,7 +2,8 @@
   "name": "@docusaurus/theme-search-algolia",
   "version": "2.0.0-beta.9",
   "description": "Algolia search component for Docusaurus.",
-  "main": "src/index.js",
+  "main": "lib/index.js",
+  "types": "src/theme-search-algolia.d.ts",
   "publishConfig": {
     "access": "public"
   },
@@ -12,6 +13,12 @@
     "directory": "packages/docusaurus-theme-search-algolia"
   },
   "license": "MIT",
+  "scripts": {
+    "build": "yarn build:server && yarn build:browser && yarn build:copy",
+    "build:server": "tsc --project tsconfig.server.json",
+    "build:browser": "tsc --project tsconfig.browser.json",
+    "build:copy": "node copyUntypedFiles.js"
+  },
   "dependencies": {
     "@docsearch/react": "^3.0.0-alpha.39",
     "@docusaurus/core": "2.0.0-beta.9",
@@ -24,6 +31,10 @@
     "eta": "^1.12.3",
     "lodash": "^4.17.20"
   },
+  "devDependencies": {
+    "@docusaurus/module-type-aliases": "2.0.0-beta.9",
+    "fs-extra": "^10.0.0"
+  },
   "peerDependencies": {
     "react": "^16.8.4 || ^17.0.0",
     "react-dom": "^16.8.4 || ^17.0.0"
diff --git a/packages/docusaurus-theme-search-algolia/src/index.js b/packages/docusaurus-theme-search-algolia/src/index.ts
similarity index 70%
rename from packages/docusaurus-theme-search-algolia/src/index.js
rename to packages/docusaurus-theme-search-algolia/src/index.ts
index e0988535f20a..dba9b8e2c32a 100644
--- a/packages/docusaurus-theme-search-algolia/src/index.js
+++ b/packages/docusaurus-theme-search-algolia/src/index.ts
@@ -5,26 +5,33 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-const path = require('path');
-const fs = require('fs');
-const eta = require('eta');
-const {normalizeUrl, getSwizzledComponent} = require('@docusaurus/utils');
-const openSearchTemplate = require('./templates/opensearch');
-const {validateThemeConfig} = require('./validateThemeConfig');
-const {memoize} = require('lodash');
+import path from 'path';
+import fs from 'fs';
+import {defaultConfig, compile} from 'eta';
+import {normalizeUrl, getSwizzledComponent} from '@docusaurus/utils';
+import openSearchTemplate from './templates/opensearch';
+import {memoize} from 'lodash';
+
+import type {DocusaurusContext, Plugin} from '@docusaurus/types';
 
 const getCompiledOpenSearchTemplate = memoize(() => {
-  return eta.compile(openSearchTemplate.trim());
+  return compile(openSearchTemplate.trim());
 });
 
-function renderOpenSearchTemplate(data) {
+function renderOpenSearchTemplate(data: {
+  title: string;
+  url: string;
+  favicon: string | null;
+}) {
   const compiled = getCompiledOpenSearchTemplate();
-  return compiled(data, eta.defaultConfig);
+  return compiled(data, defaultConfig);
 }
 
 const OPEN_SEARCH_FILENAME = 'opensearch.xml';
 
-function theme(context) {
+export default function theme(
+  context: DocusaurusContext & {baseUrl: string},
+): Plugin<void> {
   const {
     baseUrl,
     siteConfig: {title, url, favicon},
@@ -37,12 +44,16 @@ function theme(context) {
   return {
     name: 'docusaurus-theme-search-algolia',
 
+    getPathsToWatch() {
+      return [pagePath];
+    },
+
     getThemePath() {
       return path.resolve(__dirname, './theme');
     },
 
-    getPathsToWatch() {
-      return [pagePath];
+    getTypeScriptThemePath() {
+      return path.resolve(__dirname, '..', 'src', 'theme');
     },
 
     async contentLoaded({actions: {addRoute}}) {
@@ -87,6 +98,4 @@ function theme(context) {
   };
 }
 
-module.exports = theme;
-
-theme.validateThemeConfig = validateThemeConfig;
+export {validateThemeConfig} from './validateThemeConfig';
diff --git a/packages/docusaurus-theme-search-algolia/src/templates/opensearch.js b/packages/docusaurus-theme-search-algolia/src/templates/opensearch.ts
similarity index 97%
rename from packages/docusaurus-theme-search-algolia/src/templates/opensearch.js
rename to packages/docusaurus-theme-search-algolia/src/templates/opensearch.ts
index 75e974f44c66..04295bdde55e 100644
--- a/packages/docusaurus-theme-search-algolia/src/templates/opensearch.js
+++ b/packages/docusaurus-theme-search-algolia/src/templates/opensearch.ts
@@ -5,7 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-module.exports = `
+export default `
 <?xml version="1.0" encoding="UTF-8"?>
 <OpenSearchDescription xmlns="http://a9.com/-/spec/opensearch/1.1/"
                        xmlns:moz="http://www.mozilla.org/2006/browser/search/">
diff --git a/packages/docusaurus-theme-search-algolia/src/theme-search-algolia.d.ts b/packages/docusaurus-theme-search-algolia/src/theme-search-algolia.d.ts
new file mode 100644
index 000000000000..e93073b41f65
--- /dev/null
+++ b/packages/docusaurus-theme-search-algolia/src/theme-search-algolia.d.ts
@@ -0,0 +1,49 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+declare module '@docusaurus/theme-search-algolia' {
+  export type Options = never;
+}
+
+declare module '@theme/hooks/useSearchQuery' {
+  export interface SearchQuery {
+    searchQuery: string;
+
+    setSearchQuery(newSearchQuery: string): void;
+
+    generateSearchPageLink(targetSearchQuery: string): string;
+  }
+
+  export default function useSearchQuery(): SearchQuery;
+}
+
+declare module '@theme/hooks/useAlgoliaContextualFacetFilters' {
+  export type useAlgoliaContextualFacetFiltersReturns = [string, string[]];
+
+  export default function useAlgoliaContextualFacetFilters(): useAlgoliaContextualFacetFiltersReturns;
+}
+
+declare module '@theme/SearchPage' {
+  const SearchPage: () => JSX.Element;
+  export default SearchPage;
+}
+
+declare module '@theme/SearchMetadata' {
+  export type SearchMetadataProps = {
+    readonly locale?: string;
+    readonly version?: string;
+    readonly tag?: string;
+  };
+
+  const SearchMetadata: (props: SearchMetadataProps) => JSX.Element;
+  export default SearchMetadata;
+}
+
+declare module '@theme/SearchBar' {
+  const SearchBar: () => JSX.Element;
+  export default SearchBar;
+}
diff --git a/packages/docusaurus-theme-search-algolia/src/theme/SearchBar/index.js b/packages/docusaurus-theme-search-algolia/src/theme/SearchBar/index.tsx
similarity index 72%
rename from packages/docusaurus-theme-search-algolia/src/theme/SearchBar/index.js
rename to packages/docusaurus-theme-search-algolia/src/theme/SearchBar/index.tsx
index b61c86f418fa..9cd2e6cb0949 100644
--- a/packages/docusaurus-theme-search-algolia/src/theme/SearchBar/index.js
+++ b/packages/docusaurus-theme-search-algolia/src/theme/SearchBar/index.tsx
@@ -4,6 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  */
+/* eslint-disable @typescript-eslint/ban-ts-comment */
 
 import React, {useState, useRef, useCallback, useMemo} from 'react';
 import {createPortal} from 'react-dom';
@@ -19,13 +20,42 @@ import useAlgoliaContextualFacetFilters from '@theme/hooks/useAlgoliaContextualF
 import {translate} from '@docusaurus/Translate';
 import styles from './styles.module.css';
 
-let DocSearchModal = null;
+import type {
+  DocSearchModal as DocSearchModalType,
+  DocSearchModalProps,
+} from '@docsearch/react';
+import type {
+  InternalDocSearchHit,
+  StoredDocSearchHit,
+} from '@docsearch/react/dist/esm/types';
+import type {AutocompleteState} from '@algolia/autocomplete-core';
 
-function Hit({hit, children}) {
+type DocSearchProps = Omit<
+  DocSearchModalProps,
+  'onClose' | 'initialScrollY'
+> & {
+  contextualSearch?: string;
+  externalUrlRegex?: string;
+};
+
+let DocSearchModal: typeof DocSearchModalType | null = null;
+
+function Hit({
+  hit,
+  children,
+}: {
+  hit: InternalDocSearchHit | StoredDocSearchHit;
+  children: React.ReactNode;
+}) {
   return <Link to={hit.url}>{children}</Link>;
 }
 
-function ResultsFooter({state, onClose}) {
+type ResultsFooterProps = {
+  state: AutocompleteState<InternalDocSearchHit>;
+  onClose: () => void;
+};
+
+function ResultsFooter({state, onClose}: ResultsFooterProps) {
   const {generateSearchPageLink} = useSearchQuery();
 
   return (
@@ -35,7 +65,11 @@ function ResultsFooter({state, onClose}) {
   );
 }
 
-function DocSearch({contextualSearch, externalUrlRegex, ...props}) {
+function DocSearch({
+  contextualSearch,
+  externalUrlRegex,
+  ...props
+}: DocSearchProps) {
   const {siteMetadata} = useDocusaurusContext();
 
   const contextualSearchFacetFilters = useAlgoliaContextualFacetFilters();
@@ -56,10 +90,12 @@ function DocSearch({contextualSearch, externalUrlRegex, ...props}) {
 
   const {withBaseUrl} = useBaseUrlUtils();
   const history = useHistory();
-  const searchContainer = useRef(null);
-  const searchButtonRef = useRef(null);
+  const searchContainer = useRef<HTMLDivElement | null>(null);
+  const searchButtonRef = useRef<HTMLButtonElement>(null);
   const [isOpen, setIsOpen] = useState(false);
-  const [initialQuery, setInitialQuery] = useState(null);
+  const [initialQuery, setInitialQuery] = useState<string | undefined>(
+    undefined,
+  );
 
   const importDocSearchModalIfNeeded = useCallback(() => {
     if (DocSearchModal) {
@@ -67,7 +103,9 @@ function DocSearch({contextualSearch, externalUrlRegex, ...props}) {
     }
 
     return Promise.all([
+      // @ts-ignore
       import('@docsearch/react/modal'),
+      // @ts-ignore
       import('@docsearch/react/style'),
       import('./styles.css'),
     ]).then(([{DocSearchModal: Modal}]) => {
@@ -88,7 +126,7 @@ function DocSearch({contextualSearch, externalUrlRegex, ...props}) {
 
   const onClose = useCallback(() => {
     setIsOpen(false);
-    searchContainer.current.remove();
+    searchContainer.current?.remove();
   }, [setIsOpen]);
 
   const onInput = useCallback(
@@ -102,35 +140,38 @@ function DocSearch({contextualSearch, externalUrlRegex, ...props}) {
   );
 
   const navigator = useRef({
-    navigate({itemUrl}) {
+    navigate({itemUrl}: {itemUrl?: string}) {
       // Algolia results could contain URL's from other domains which cannot
       // be served through history and should navigate with window.location
       if (isRegexpStringMatch(externalUrlRegex, itemUrl)) {
-        window.location.href = itemUrl;
+        window.location.href = itemUrl!;
       } else {
-        history.push(itemUrl);
+        history.push(itemUrl!);
       }
     },
   }).current;
 
-  const transformItems = useRef((items) => {
-    return items.map((item) => {
-      // If Algolia contains a external domain, we should navigate without relative URL
-      if (isRegexpStringMatch(externalUrlRegex, item.url)) {
-        return item;
-      }
+  const transformItems = useRef<DocSearchModalProps['transformItems']>(
+    (items) => {
+      return items.map((item) => {
+        // If Algolia contains a external domain, we should navigate without relative URL
+        if (isRegexpStringMatch(externalUrlRegex, item.url)) {
+          return item;
+        }
 
-      // We transform the absolute URL into a relative URL.
-      const url = new URL(item.url);
-      return {
-        ...item,
-        url: withBaseUrl(`${url.pathname}${url.hash}`),
-      };
-    });
-  }).current;
+        // We transform the absolute URL into a relative URL.
+        const url = new URL(item.url);
+        return {
+          ...item,
+          url: withBaseUrl(`${url.pathname}${url.hash}`),
+        };
+      });
+    },
+  ).current;
 
   const resultsFooterComponent = useMemo(
-    () => (footerProps) => <ResultsFooter {...footerProps} onClose={onClose} />,
+    () => (footerProps: ResultsFooterProps) =>
+      <ResultsFooter {...footerProps} onClose={onClose} />,
     [onClose],
   );
 
@@ -188,6 +229,8 @@ function DocSearch({contextualSearch, externalUrlRegex, ...props}) {
       </div>
 
       {isOpen &&
+        DocSearchModal &&
+        searchContainer.current &&
         createPortal(
           <DocSearchModal
             onClose={onClose}
@@ -209,6 +252,7 @@ function DocSearch({contextualSearch, externalUrlRegex, ...props}) {
 
 function SearchBar() {
   const {siteConfig} = useDocusaurusContext();
+  // @ts-ignore
   return <DocSearch {...siteConfig.themeConfig.algolia} />;
 }
 
diff --git a/packages/docusaurus-theme-search-algolia/src/theme/SearchMetadata/index.js b/packages/docusaurus-theme-search-algolia/src/theme/SearchMetadata/index.tsx
similarity index 80%
rename from packages/docusaurus-theme-search-algolia/src/theme/SearchMetadata/index.js
rename to packages/docusaurus-theme-search-algolia/src/theme/SearchMetadata/index.tsx
index 584ce2a9c3c2..1984d7221f5c 100644
--- a/packages/docusaurus-theme-search-algolia/src/theme/SearchMetadata/index.js
+++ b/packages/docusaurus-theme-search-algolia/src/theme/SearchMetadata/index.tsx
@@ -8,9 +8,14 @@
 import React from 'react';
 
 import Head from '@docusaurus/Head';
+import type {SearchMetadataProps} from '@theme/SearchMetadata';
 
 // Override default/agnostic SearchMetas to use Algolia-specific metadata
-export default function AlgoliaSearchMetadata({locale, version, tag}) {
+function SearchMetadata({
+  locale,
+  version,
+  tag,
+}: SearchMetadataProps): JSX.Element {
   // Seems safe to consider here the locale is the language,
   // as the existing docsearch:language filter is afaik a regular string-based filter
   const language = locale;
@@ -23,3 +28,5 @@ export default function AlgoliaSearchMetadata({locale, version, tag}) {
     </Head>
   );
 }
+
+export default SearchMetadata;
diff --git a/packages/docusaurus-theme-search-algolia/src/theme/SearchPage/index.js b/packages/docusaurus-theme-search-algolia/src/theme/SearchPage/index.tsx
similarity index 91%
rename from packages/docusaurus-theme-search-algolia/src/theme/SearchPage/index.js
rename to packages/docusaurus-theme-search-algolia/src/theme/SearchPage/index.tsx
index b89e233f7891..18e9231d5dd2 100644
--- a/packages/docusaurus-theme-search-algolia/src/theme/SearchPage/index.js
+++ b/packages/docusaurus-theme-search-algolia/src/theme/SearchPage/index.tsx
@@ -6,6 +6,7 @@
  */
 
 /* eslint-disable jsx-a11y/no-autofocus */
+/* eslint-disable @typescript-eslint/ban-ts-comment */
 
 import React, {useEffect, useState, useReducer, useRef} from 'react';
 
@@ -32,7 +33,7 @@ import styles from './styles.module.css';
 // Very simple pluralization: probably good enough for now
 function useDocumentsFoundPlural() {
   const {selectMessage} = usePluralForm();
-  return (count) =>
+  return (count: number) =>
     selectMessage(
       count,
       translate(
@@ -52,14 +53,19 @@ function useDocsSearchVersionsHelpers() {
 
   // State of the version select menus / algolia facet filters
   // docsPluginId -> versionName map
-  const [searchVersions, setSearchVersions] = useState(() => {
-    return Object.entries(allDocsData).reduce((acc, [pluginId, pluginData]) => {
-      return {...acc, [pluginId]: pluginData.versions[0].name};
-    }, {});
-  });
+  const [searchVersions, setSearchVersions] = useState<Record<string, string>>(
+    () => {
+      return Object.entries(allDocsData).reduce(
+        (acc, [pluginId, pluginData]) => {
+          return {...acc, [pluginId]: pluginData.versions[0].name};
+        },
+        {},
+      );
+    },
+  );
 
   // Set the value of a single select menu
-  const setSearchVersion = (pluginId, searchVersion) =>
+  const setSearchVersion = (pluginId: string, searchVersion: string) =>
     setSearchVersions((s) => ({...s, [pluginId]: searchVersion}));
 
   const versioningEnabled = Object.values(allDocsData).some(
@@ -75,7 +81,11 @@ function useDocsSearchVersionsHelpers() {
 }
 
 // We want to display one select per versioned docs plugin instance
-const SearchVersionSelectList = ({docsSearchVersionsHelpers}) => {
+const SearchVersionSelectList = ({
+  docsSearchVersionsHelpers,
+}: {
+  docsSearchVersionsHelpers: ReturnType<typeof useDocsSearchVersionsHelpers>;
+}) => {
   const versionedPluginEntries = Object.entries(
     docsSearchVersionsHelpers.allDocsData,
   )
@@ -118,10 +128,32 @@ const SearchVersionSelectList = ({docsSearchVersionsHelpers}) => {
   );
 };
 
-function SearchPage() {
+type ResultDispatcherState = {
+  items: {
+    title: string;
+    url: string;
+    summary: string;
+    breadcrumbs: string[];
+  }[];
+  query: string | null;
+  totalResults: number | null;
+  totalPages: number | null;
+  lastPage: number | null;
+  hasMore: boolean | null;
+  loading: boolean | null;
+};
+
+type ResultDispatcher =
+  | {type: 'reset'; value?: undefined}
+  | {type: 'loading'; value?: undefined}
+  | {type: 'update'; value: ResultDispatcherState}
+  | {type: 'advance'; value?: undefined};
+
+function SearchPage(): JSX.Element {
   const {
     siteConfig: {
       themeConfig: {
+        // @ts-ignore
         algolia: {appId, apiKey, indexName, externalUrlRegex},
       },
     },
@@ -131,7 +163,7 @@ function SearchPage() {
 
   const docsSearchVersionsHelpers = useDocsSearchVersionsHelpers();
   const {searchQuery, setSearchQuery} = useSearchQuery();
-  const initialSearchResultState = {
+  const initialSearchResultState: ResultDispatcherState = {
     items: [],
     query: null,
     totalResults: null,
@@ -141,8 +173,8 @@ function SearchPage() {
     loading: null,
   };
   const [searchResultState, searchResultStateDispatcher] = useReducer(
-    (prevState, {type, value: state}) => {
-      switch (type) {
+    (prevState: ResultDispatcherState, data: ResultDispatcher) => {
+      switch (data.type) {
         case 'reset': {
           return initialSearchResultState;
         }
@@ -150,24 +182,24 @@ function SearchPage() {
           return {...prevState, loading: true};
         }
         case 'update': {
-          if (searchQuery !== state.query) {
+          if (searchQuery !== data.value.query) {
             return prevState;
           }
 
           return {
-            ...state,
+            ...data.value,
             items:
-              state.lastPage === 0
-                ? state.items
-                : prevState.items.concat(state.items),
+              data.value.lastPage === 0
+                ? data.value.items
+                : prevState.items.concat(data.value.items),
           };
         }
         case 'advance': {
-          const hasMore = prevState.totalPages > prevState.lastPage + 1;
+          const hasMore = prevState.totalPages! > prevState.lastPage! + 1;
 
           return {
             ...prevState,
-            lastPage: hasMore ? prevState.lastPage + 1 : prevState.lastPage,
+            lastPage: hasMore ? prevState.lastPage! + 1 : prevState.lastPage,
             hasMore,
           };
         }
@@ -193,7 +225,7 @@ function SearchPage() {
         return;
       }
 
-      const sanitizeValue = (value) => {
+      const sanitizeValue = (value: string) => {
         return value.replace(
           /algolia-docsearch-suggestion--highlight/g,
           'search-result-match',
@@ -212,7 +244,7 @@ function SearchPage() {
           });
 
           return {
-            title: titles.pop(),
+            title: titles.pop()!,
             url: isRegexpStringMatch(externalUrlRegex, parsedURL.href)
               ? parsedURL.href
               : parsedURL.pathname + parsedURL.hash,
@@ -239,7 +271,7 @@ function SearchPage() {
     },
   );
 
-  const [loaderRef, setLoaderRef] = useState(null);
+  const [loaderRef, setLoaderRef] = useState<HTMLDivElement | null>(null);
   const prevY = useRef(0);
   const observer = useRef(
     ExecutionEnvironment.canUseDOM &&
@@ -278,7 +310,7 @@ function SearchPage() {
           description: 'The search page title for empty query',
         });
 
-  const makeSearch = useDynamicCallback((page = 0) => {
+  const makeSearch = useDynamicCallback((page: number = 0) => {
     algoliaHelper.addDisjunctiveFacetRefinement('docusaurus_tag', 'default');
     algoliaHelper.addDisjunctiveFacetRefinement('language', currentLocale);
 
@@ -299,9 +331,11 @@ function SearchPage() {
       return undefined;
     }
     const currentObserver = observer.current;
-
-    currentObserver.observe(loaderRef);
-    return () => currentObserver.unobserve(loaderRef);
+    if (currentObserver) {
+      currentObserver.observe(loaderRef);
+      return () => currentObserver.unobserve(loaderRef);
+    }
+    return () => true;
   }, [loaderRef]);
 
   useEffect(() => {
diff --git a/packages/docusaurus-theme-search-algolia/src/theme/hooks/useAlgoliaContextualFacetFilters.js b/packages/docusaurus-theme-search-algolia/src/theme/hooks/useAlgoliaContextualFacetFilters.ts
similarity index 66%
rename from packages/docusaurus-theme-search-algolia/src/theme/hooks/useAlgoliaContextualFacetFilters.js
rename to packages/docusaurus-theme-search-algolia/src/theme/hooks/useAlgoliaContextualFacetFilters.ts
index 3ee15f665d16..a1ca093d0ab9 100644
--- a/packages/docusaurus-theme-search-algolia/src/theme/hooks/useAlgoliaContextualFacetFilters.js
+++ b/packages/docusaurus-theme-search-algolia/src/theme/hooks/useAlgoliaContextualFacetFilters.ts
@@ -5,10 +5,11 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import useContextualSearchFilters from '@theme/hooks/useContextualSearchFilters';
+import type {useAlgoliaContextualFacetFiltersReturns} from '@theme/hooks/useAlgoliaContextualFacetFilters';
+import {useContextualSearchFilters} from '@docusaurus/theme-common';
 
 // Translate search-engine agnostic search filters to Algolia search filters
-export default function useAlgoliaContextualFacetFilters() {
+export default function useAlgoliaContextualFacetFilters(): useAlgoliaContextualFacetFiltersReturns {
   const {locale, tags} = useContextualSearchFilters();
 
   // seems safe to convert locale->language, see AlgoliaSearchMetadata comment
diff --git a/packages/docusaurus-theme-search-algolia/src/theme/hooks/useSearchQuery.js b/packages/docusaurus-theme-search-algolia/src/theme/hooks/useSearchQuery.ts
similarity index 89%
rename from packages/docusaurus-theme-search-algolia/src/theme/hooks/useSearchQuery.js
rename to packages/docusaurus-theme-search-algolia/src/theme/hooks/useSearchQuery.ts
index 5789251fa814..7667f4de2360 100644
--- a/packages/docusaurus-theme-search-algolia/src/theme/hooks/useSearchQuery.js
+++ b/packages/docusaurus-theme-search-algolia/src/theme/hooks/useSearchQuery.ts
@@ -8,10 +8,11 @@
 import {useHistory} from '@docusaurus/router';
 import useDocusaurusContext from '@docusaurus/useDocusaurusContext';
 import {useCallback, useEffect, useState} from 'react';
+import type {SearchQuery} from '@theme/hooks/useSearchQuery';
 
 const SEARCH_PARAM_QUERY = 'q';
 
-function useSearchQuery() {
+function useSearchQuery(): SearchQuery {
   const history = useHistory();
   const {
     siteConfig: {baseUrl},
@@ -28,7 +29,7 @@ function useSearchQuery() {
   }, []);
 
   const setSearchQuery = useCallback(
-    (newSearchQuery) => {
+    (newSearchQuery: string) => {
       const searchParams = new URLSearchParams(window.location.search);
 
       if (newSearchQuery) {
@@ -46,7 +47,7 @@ function useSearchQuery() {
   );
 
   const generateSearchPageLink = useCallback(
-    (targetSearchQuery) => {
+    (targetSearchQuery: string) => {
       // Refer to https://github.com/facebook/docusaurus/pull/2838
       return `${baseUrl}search?q=${encodeURIComponent(targetSearchQuery)}`;
     },
diff --git a/packages/docusaurus-theme-search-algolia/src/types.d.ts b/packages/docusaurus-theme-search-algolia/src/types.d.ts
new file mode 100644
index 000000000000..04ccef3c4442
--- /dev/null
+++ b/packages/docusaurus-theme-search-algolia/src/types.d.ts
@@ -0,0 +1,10 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+/// <reference types="@docusaurus/module-type-aliases" />
+/// <reference types="@docusaurus/theme-common" />
+/// <reference types="@docusaurus/theme-classic" />
diff --git a/packages/docusaurus-theme-search-algolia/src/validateThemeConfig.js b/packages/docusaurus-theme-search-algolia/src/validateThemeConfig.ts
similarity index 78%
rename from packages/docusaurus-theme-search-algolia/src/validateThemeConfig.js
rename to packages/docusaurus-theme-search-algolia/src/validateThemeConfig.ts
index 8cfe4bfed9e3..b2afb4c1aa84 100644
--- a/packages/docusaurus-theme-search-algolia/src/validateThemeConfig.js
+++ b/packages/docusaurus-theme-search-algolia/src/validateThemeConfig.ts
@@ -5,7 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-const {Joi} = require('@docusaurus/utils-validation');
+import {Joi} from '@docusaurus/utils-validation';
+import type {ThemeConfig, Validate, ValidationResult} from '@docusaurus/types';
 
 const DEFAULT_CONFIG = {
   contextualSearch: false, // future: maybe we want to enable this by default
@@ -18,7 +19,7 @@ const DEFAULT_CONFIG = {
 };
 exports.DEFAULT_CONFIG = DEFAULT_CONFIG;
 
-const Schema = Joi.object({
+export const Schema = Joi.object({
   algolia: Joi.object({
     // Docusaurus attributes
     contextualSearch: Joi.boolean().default(DEFAULT_CONFIG.contextualSearch),
@@ -35,11 +36,13 @@ const Schema = Joi.object({
     .required()
     .unknown(), // DocSearch 3 is still alpha: don't validate the rest for now
 });
-exports.Schema = Schema;
 
-exports.validateThemeConfig = function validateThemeConfig({
+export function validateThemeConfig({
   validate,
   themeConfig,
-}) {
+}: {
+  validate: Validate<ThemeConfig>;
+  themeConfig: ThemeConfig;
+}): ValidationResult<ThemeConfig> {
   return validate(Schema, themeConfig);
-};
+}
diff --git a/packages/docusaurus-theme-search-algolia/tsconfig.browser.json b/packages/docusaurus-theme-search-algolia/tsconfig.browser.json
new file mode 100644
index 000000000000..3af8257cdf8d
--- /dev/null
+++ b/packages/docusaurus-theme-search-algolia/tsconfig.browser.json
@@ -0,0 +1,8 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "module": "esnext",
+    "jsx": "react-native"
+  },
+  "include": ["src/theme/", "src/*.d.ts"]
+}
diff --git a/packages/docusaurus-theme-search-algolia/tsconfig.json b/packages/docusaurus-theme-search-algolia/tsconfig.json
new file mode 100644
index 000000000000..4b7c4f42a698
--- /dev/null
+++ b/packages/docusaurus-theme-search-algolia/tsconfig.json
@@ -0,0 +1,9 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "lib": ["DOM", "ES2019"],
+    "rootDir": "src",
+    "baseUrl": "src",
+    "outDir": "lib"
+  }
+}
diff --git a/packages/docusaurus-theme-search-algolia/tsconfig.server.json b/packages/docusaurus-theme-search-algolia/tsconfig.server.json
new file mode 100644
index 000000000000..3faf6c3e997b
--- /dev/null
+++ b/packages/docusaurus-theme-search-algolia/tsconfig.server.json
@@ -0,0 +1,4 @@
+{
+  "extends": "./tsconfig.json",
+  "include": ["src/*.ts", "src/templates/*.ts"]
+}