diff --git a/src/lib/booru/TagsUtils.js b/src/lib/booru/TagsUtils.js
deleted file mode 100644
index c430c4c..0000000
--- a/src/lib/booru/TagsUtils.js
+++ /dev/null
@@ -1,34 +0,0 @@
-/**
- * Build the map containing both real tags and their aliases.
- *
- * @param {string[]} realAndAliasedTags List combining aliases and tag names.
- * @param {string[]} realTags List of actual tag names, excluding aliases.
- *
- * @return {Map<string, string>} Map where key is a tag or alias and value is an actual tag name.
- */
-export function buildTagsAndAliasesMap(realAndAliasedTags, realTags) {
-  /** @type {Map<string, string>} */
-  const tagsAndAliasesMap = new Map();
-
-  for (let tagName of realTags) {
-    tagsAndAliasesMap.set(tagName, tagName);
-  }
-
-  let realTagName = null;
-
-  for (let tagNameOrAlias of realAndAliasedTags) {
-    if (tagsAndAliasesMap.has(tagNameOrAlias)) {
-      realTagName = tagNameOrAlias;
-      continue;
-    }
-
-    if (!realTagName) {
-      console.warn('No real tag found for the alias:', tagNameOrAlias);
-      continue;
-    }
-
-    tagsAndAliasesMap.set(tagNameOrAlias, realTagName);
-  }
-
-  return tagsAndAliasesMap;
-}
diff --git a/src/lib/booru/scraped/parsing/PostParser.js b/src/lib/booru/scraped/parsing/PostParser.js
index bac254d..af6d104 100644
--- a/src/lib/booru/scraped/parsing/PostParser.js
+++ b/src/lib/booru/scraped/parsing/PostParser.js
@@ -1,5 +1,5 @@
 import PageParser from "$lib/booru/scraped/parsing/PageParser";
-import { buildTagsAndAliasesMap } from "$lib/booru/TagsUtils";
+import { buildTagsAndAliasesMap } from "$lib/booru/tag-utils";
 
 export default class PostParser extends PageParser {
   /** @type {HTMLFormElement} */
diff --git a/src/lib/booru/search/QueryLexer.js b/src/lib/booru/search/QueryLexer.ts
similarity index 69%
rename from src/lib/booru/search/QueryLexer.js
rename to src/lib/booru/search/QueryLexer.ts
index 07e9c22..76d2d5f 100644
--- a/src/lib/booru/search/QueryLexer.js
+++ b/src/lib/booru/search/QueryLexer.ts
@@ -1,8 +1,8 @@
 export class Token {
-  index;
-  value;
+  readonly index: number;
+  readonly value: string;
 
-  constructor(index, value) {
+  constructor(index: number, value: string) {
     this.index = index;
     this.value = value;
   }
@@ -28,12 +28,9 @@ export class BoostToken extends Token {
 }
 
 export class QuotedTermToken extends Token {
-  /**
-   * @type {string}
-   */
-  #quotedValue;
+  readonly #quotedValue: string;
 
-  constructor(index, value, quotedValue) {
+  constructor(index: number, value: string, quotedValue: string) {
     super(index, value);
 
     this.#quotedValue = quotedValue;
@@ -43,19 +40,11 @@ export class QuotedTermToken extends Token {
     return QuotedTermToken.decode(this.#quotedValue);
   }
 
-  /**
-   * @param {string} value
-   * @return {string}
-   */
-  static decode(value) {
+  static decode(value: string): string {
     return value.replace(/\\([\\"])/g, "$1");
   }
 
-  /**
-   * @param {string} value
-   * @return {string}
-   */
-  static encode(value) {
+  static encode(value: string): string {
     return value.replace(/[\\"]/g, "\\$&");
   }
 }
@@ -63,6 +52,10 @@ export class QuotedTermToken extends Token {
 export class TermToken extends Token {
 }
 
+type MatchResultCarry = {
+  match?: RegExpMatchArray | null
+}
+
 /**
  * Search query tokenizer. Should mostly work for the cases of parsing and finding the selected term for
  * auto-completion. Follows the rules described in the Philomena booru engine.
@@ -70,38 +63,28 @@ export class TermToken extends Token {
 export class QueryLexer {
   /**
    * The original value to be parsed.
-   * @type {string}
    */
-  #value;
+  readonly #value: string;
 
   /**
    * Current position of the parser in the value.
-   * @type {number}
    */
-  #index = 0;
+  #index: number = 0;
 
-  /**
-   * @param {string} value
-   */
-  constructor(value) {
+  constructor(value: string) {
     this.#value = value;
   }
 
   /**
    * Parse the query and get the list of tokens.
    *
-   * @return {Token[]} List of tokens.
+   * @return List of tokens.
    */
-  parse() {
-    /** @type {Token[]} */
-    const tokens = [];
+  parse(): Token[] {
+    const tokens: Token[] = [];
+    const result: MatchResultCarry = {};
 
-    /**
-     * @type {{match: RegExpMatchArray|null}}
-     */
-    const result = {};
-
-    let dirtyText;
+    let dirtyText: string;
 
     while (this.#index < this.#value.length) {
       if (this.#value[this.#index] === QueryLexer.#commaCharacter) {
@@ -111,26 +94,26 @@ export class QueryLexer {
       }
 
       if (this.#match(QueryLexer.#negotiationOperator, result)) {
-        tokens.push(new NotToken(this.#index, result.match[0]));
-        this.#index += result.match[0].length;
+        tokens.push(new NotToken(this.#index, result.match![0]));
+        this.#index += result.match![0].length;
         continue;
       }
 
       if (this.#match(QueryLexer.#andOperator, result)) {
-        tokens.push(new AndToken(this.#index, result.match[0]));
-        this.#index += result.match[0].length;
+        tokens.push(new AndToken(this.#index, result.match![0]));
+        this.#index += result.match![0].length;
         continue;
       }
 
       if (this.#match(QueryLexer.#orOperator, result)) {
-        tokens.push(new OrToken(this.#index, result.match[0]));
-        this.#index += result.match[0].length;
+        tokens.push(new OrToken(this.#index, result.match![0]));
+        this.#index += result.match![0].length;
         continue;
       }
 
       if (this.#match(QueryLexer.#notOperator, result)) {
-        tokens.push(new NotToken(this.#index, result.match[0]));
-        this.#index += result.match[0].length;
+        tokens.push(new NotToken(this.#index, result.match![0]));
+        this.#index += result.match![0].length;
         continue;
       }
 
@@ -147,19 +130,19 @@ export class QueryLexer {
       }
 
       if (this.#match(QueryLexer.#boostOperator, result)) {
-        tokens.push(new BoostToken(this.#index, result.match[0]));
-        this.#index += result.match[0].length;
+        tokens.push(new BoostToken(this.#index, result.match![0]));
+        this.#index += result.match![0].length;
         continue;
       }
 
       if (this.#match(QueryLexer.#whitespaces, result)) {
-        this.#index += result.match[0].length;
+        this.#index += result.match![0].length;
         continue;
       }
 
       if (this.#match(QueryLexer.#quotedText, result)) {
-        tokens.push(new QuotedTermToken(this.#index, result.match[0], result.match[1]));
-        this.#index += result.match[0].length;
+        tokens.push(new QuotedTermToken(this.#index, result.match![0], result.match![1]));
+        this.#index += result.match![0].length;
         continue;
       }
 
@@ -180,25 +163,25 @@ export class QueryLexer {
   /**
    * Match the provided regular expression on the string with the current parser position.
    *
-   * @param {RegExp} targetRegExp Target RegExp to parse with.
-   * @param {{match: any}} [resultCarrier] Object for passing the results into.
+   * @param targetRegExp Target RegExp to parse with.
+   * @param [resultCarrier] Object for passing the results into.
    *
-   * @return {boolean} Is there a match?
+   * @return Is there a match?
    */
-  #match(targetRegExp, resultCarrier = {}) {
+  #match(targetRegExp: RegExp, resultCarrier: MatchResultCarry = {}): boolean {
     return this.#matchAt(targetRegExp, this.#index, resultCarrier);
   }
 
   /**
    * Match the provided regular expression in the string with the specific index.
    *
-   * @param {RegExp} targetRegExp Target RegExp to parse with.
-   * @param {number} index Index to match the expression from.
-   * @param {{match: any}} [resultCarrier] Object for passing the results into.
+   * @param targetRegExp Target RegExp to parse with.
+   * @param index Index to match the expression from.
+   * @param [resultCarrier] Object for passing the results into.
    *
-   * @return {boolean} Is there a match?
+   * @return Is there a match?
    */
-  #matchAt(targetRegExp, index, resultCarrier = {}) {
+  #matchAt(targetRegExp: RegExp, index: number, resultCarrier: MatchResultCarry = {}): boolean {
     targetRegExp.lastIndex = index;
     resultCarrier.match = this.#value.match(targetRegExp);
 
@@ -212,11 +195,10 @@ export class QueryLexer {
    *
    * @return {string} Matched text.
    */
-  #parseDirtyText(index) {
-    let resultValue = '';
+  #parseDirtyText(index: number): string {
+    let resultValue: string = '';
 
-    /** @type {{match: RegExpMatchArray|null}} */
-    const result = {match: null};
+    const result: MatchResultCarry = {match: null};
 
     // Loop over
     while (index < this.#value.length) {
@@ -226,8 +208,8 @@ export class QueryLexer {
       }
 
       if (this.#matchAt(QueryLexer.#dirtyTextContent, index, result)) {
-        resultValue += result.match[0];
-        index += result.match[0].length;
+        resultValue += result.match![0];
+        index += result.match![0].length;
         continue;
       }
 
diff --git a/src/lib/booru/tag-categories.js b/src/lib/booru/tag-categories.ts
similarity index 100%
rename from src/lib/booru/tag-categories.js
rename to src/lib/booru/tag-categories.ts
diff --git a/src/lib/booru/tag-utils.ts b/src/lib/booru/tag-utils.ts
new file mode 100644
index 0000000..3270685
--- /dev/null
+++ b/src/lib/booru/tag-utils.ts
@@ -0,0 +1,33 @@
+/**
+ * Build the map containing both real tags and their aliases.
+ *
+ * @param realAndAliasedTags List combining aliases and tag names.
+ * @param realTags List of actual tag names, excluding aliases.
+ *
+ * @return Map where key is a tag or alias and value is an actual tag name.
+ */
+export function buildTagsAndAliasesMap(realAndAliasedTags: string[], realTags: string[]): Map<string, string> {
+  const tagsAndAliasesMap: Map<string, string> = new Map();
+
+  for (const tagName of realTags) {
+    tagsAndAliasesMap.set(tagName, tagName);
+  }
+
+  let realTagName: string | null = null;
+
+  for (const tagNameOrAlias of realAndAliasedTags) {
+    if (tagsAndAliasesMap.has(tagNameOrAlias)) {
+      realTagName = tagNameOrAlias;
+      continue;
+    }
+
+    if (!realTagName) {
+      console.warn('No real tag found for the alias:', tagNameOrAlias);
+      continue;
+    }
+
+    tagsAndAliasesMap.set(tagNameOrAlias, realTagName);
+  }
+
+  return tagsAndAliasesMap;
+}
diff --git a/src/lib/browser/StorageHelper.js b/src/lib/browser/StorageHelper.js
deleted file mode 100644
index 1d4bf26..0000000
--- a/src/lib/browser/StorageHelper.js
+++ /dev/null
@@ -1,57 +0,0 @@
-/**
- * Helper class to read and write JSON objects to the local storage.
- * @class
- */
-class StorageHelper {
-  /**
-   * @type {chrome.storage.StorageArea}
-   */
-  #storageArea;
-
-  /**
-   * @param {chrome.storage.StorageArea} storageArea
-   */
-  constructor(storageArea) {
-    this.#storageArea = storageArea;
-  }
-
-  /**
-   * Read the following entry from the local storage as a JSON object.
-   *
-   * @param {string} key Key of the entry to read.
-   * @param {any} defaultValue Default value to return if the entry does not exist.
-   *
-   * @return {Promise<any>} The JSON object or the default value if the entry does not exist.
-   */
-  async read(key, defaultValue = null) {
-    return (await this.#storageArea.get(key))?.[key] || defaultValue;
-  }
-
-  /**
-   * Write the following JSON object to the local storage.
-   *
-   * @param {string} key Key of the entry to write.
-   * @param {any} value JSON object to write.
-   */
-  write(key, value) {
-    void this.#storageArea.set({[key]: value});
-  }
-
-  /**
-   * Subscribe to changes in the local storage.
-   * @param {function(Record<string, chrome.storage.StorageChange>): void} callback
-   */
-  subscribe(callback) {
-    this.#storageArea.onChanged.addListener(callback);
-  }
-
-  /**
-   * Unsubscribe from changes in the local storage.
-   * @param {function(Record<string, chrome.storage.StorageChange>): void} callback
-   */
-  unsubscribe(callback) {
-    this.#storageArea.onChanged.removeListener(callback);
-  }
-}
-
-export default StorageHelper;
diff --git a/src/lib/browser/StorageHelper.ts b/src/lib/browser/StorageHelper.ts
new file mode 100644
index 0000000..19c4afd
--- /dev/null
+++ b/src/lib/browser/StorageHelper.ts
@@ -0,0 +1,53 @@
+/**
+ * Changes subscribe function. It receives changes with old and new value for keys of the storage.
+ */
+export type StorageChangeSubscriber = (changes: Record<string, chrome.storage.StorageChange>) => void;
+
+/**
+ * Helper class to read and write JSON objects to the local storage.
+ */
+export default class StorageHelper {
+  readonly #storageArea: chrome.storage.StorageArea;
+
+  constructor(storageArea: chrome.storage.StorageArea) {
+    this.#storageArea = storageArea;
+  }
+
+  /**
+   * Read the following entry from the local storage as a JSON object.
+   *
+   * @param key Key of the entry to read.
+   * @param defaultValue Default value to return if the entry does not exist.
+   *
+   * @return The JSON object or the default value if the entry does not exist.
+   */
+  async read<Type = any, DefaultType = any>(key: string, defaultValue: DefaultType | null = null): Promise<Type | DefaultType> {
+    return (await this.#storageArea.get(key))?.[key] || defaultValue;
+  }
+
+  /**
+   * Write the following JSON object to the local storage.
+   *
+   * @param key Key of the entry to write.
+   * @param value Value to write.
+   */
+  write(key: string, value: any): void {
+    void this.#storageArea.set({[key]: value});
+  }
+
+  /**
+   * Subscribe to changes in the local storage.
+   * @param callback Listener function to receive changes.
+   */
+  subscribe(callback: StorageChangeSubscriber): void {
+    this.#storageArea.onChanged.addListener(callback);
+  }
+
+  /**
+   * Unsubscribe from changes in the local storage.
+   * @param callback Reference to the callback for unsubscribing.
+   */
+  unsubscribe(callback: StorageChangeSubscriber): void {
+    this.#storageArea.onChanged.removeListener(callback);
+  }
+}
diff --git a/src/lib/components/ImageShowFullscreenButton.js b/src/lib/components/ImageShowFullscreenButton.js
index 7c0b63a..fc00370 100644
--- a/src/lib/components/ImageShowFullscreenButton.js
+++ b/src/lib/components/ImageShowFullscreenButton.js
@@ -1,5 +1,5 @@
 import { BaseComponent } from "$lib/components/base/BaseComponent";
-import { getComponent } from "$lib/components/base/ComponentUtils";
+import { getComponent } from "$lib/components/base/component-utils";
 import MiscSettings from "$lib/extension/settings/MiscSettings";
 import { FullscreenViewer } from "$lib/components/FullscreenViewer";
 
diff --git a/src/lib/components/MaintenancePopup.js b/src/lib/components/MaintenancePopup.js
index 6dc1f1c..3966be1 100644
--- a/src/lib/components/MaintenancePopup.js
+++ b/src/lib/components/MaintenancePopup.js
@@ -1,7 +1,7 @@
 import MaintenanceSettings from "$lib/extension/settings/MaintenanceSettings";
 import MaintenanceProfile from "$entities/MaintenanceProfile";
 import { BaseComponent } from "$lib/components/base/BaseComponent";
-import { getComponent } from "$lib/components/base/ComponentUtils";
+import { getComponent } from "$lib/components/base/component-utils";
 import ScrapedAPI from "$lib/booru/scraped/ScrapedAPI";
 import { tagsBlacklist } from "$config/tags";
 import { emitterAt } from "$lib/components/events/comms";
diff --git a/src/lib/components/MaintenanceStatusIcon.js b/src/lib/components/MaintenanceStatusIcon.js
index 4c0423d..78ebd57 100644
--- a/src/lib/components/MaintenanceStatusIcon.js
+++ b/src/lib/components/MaintenanceStatusIcon.js
@@ -1,5 +1,5 @@
 import { BaseComponent } from "$lib/components/base/BaseComponent";
-import { getComponent } from "$lib/components/base/ComponentUtils";
+import { getComponent } from "$lib/components/base/component-utils";
 import { on } from "$lib/components/events/comms";
 import { eventMaintenanceStateChanged } from "$lib/components/events/maintenance-popup-events";
 
diff --git a/src/lib/components/MediaBoxTools.js b/src/lib/components/MediaBoxTools.js
index c7afac7..f2de6c5 100644
--- a/src/lib/components/MediaBoxTools.js
+++ b/src/lib/components/MediaBoxTools.js
@@ -1,5 +1,5 @@
 import { BaseComponent } from "$lib/components/base/BaseComponent";
-import { getComponent } from "$lib/components/base/ComponentUtils";
+import { getComponent } from "$lib/components/base/component-utils";
 import { MaintenancePopup } from "$lib/components/MaintenancePopup";
 import { on } from "$lib/components/events/comms";
 import { eventActiveProfileChanged } from "$lib/components/events/maintenance-popup-events";
diff --git a/src/lib/components/MediaBoxWrapper.js b/src/lib/components/MediaBoxWrapper.js
index 4559fd6..ff0ec34 100644
--- a/src/lib/components/MediaBoxWrapper.js
+++ b/src/lib/components/MediaBoxWrapper.js
@@ -1,6 +1,6 @@
 import { BaseComponent } from "$lib/components/base/BaseComponent";
-import { getComponent } from "$lib/components/base/ComponentUtils";
-import { buildTagsAndAliasesMap } from "$lib/booru/TagsUtils";
+import { getComponent } from "$lib/components/base/component-utils";
+import { buildTagsAndAliasesMap } from "$lib/booru/tag-utils";
 import { on } from "$lib/components/events/comms";
 import { eventTagsUpdated } from "$lib/components/events/maintenance-popup-events";
 
diff --git a/src/lib/components/TagDropdownWrapper.js b/src/lib/components/TagDropdownWrapper.js
index 4c72dd1..3b09f08 100644
--- a/src/lib/components/TagDropdownWrapper.js
+++ b/src/lib/components/TagDropdownWrapper.js
@@ -1,7 +1,7 @@
 import { BaseComponent } from "$lib/components/base/BaseComponent";
 import MaintenanceProfile from "$entities/MaintenanceProfile";
 import MaintenanceSettings from "$lib/extension/settings/MaintenanceSettings";
-import { getComponent } from "$lib/components/base/ComponentUtils";
+import { getComponent } from "$lib/components/base/component-utils";
 import CustomCategoriesResolver from "$lib/extension/CustomCategoriesResolver";
 
 const isTagEditorProcessedKey = Symbol();
diff --git a/src/lib/components/TagsForm.js b/src/lib/components/TagsForm.js
index 00cdfbc..5376ca3 100644
--- a/src/lib/components/TagsForm.js
+++ b/src/lib/components/TagsForm.js
@@ -1,5 +1,5 @@
 import { BaseComponent } from "$lib/components/base/BaseComponent";
-import { getComponent } from "$lib/components/base/ComponentUtils";
+import { getComponent } from "$lib/components/base/component-utils";
 
 export class TagsForm extends BaseComponent {
   /**
diff --git a/src/lib/components/base/BaseComponent.js b/src/lib/components/base/BaseComponent.js
index 3fd982e..04ac8fd 100644
--- a/src/lib/components/base/BaseComponent.js
+++ b/src/lib/components/base/BaseComponent.js
@@ -1,4 +1,4 @@
-import { bindComponent } from "$lib/components/base/ComponentUtils";
+import { bindComponent } from "$lib/components/base/component-utils";
 
 /**
  * @abstract
diff --git a/src/lib/components/base/ComponentUtils.js b/src/lib/components/base/ComponentUtils.js
deleted file mode 100644
index 768621f..0000000
--- a/src/lib/components/base/ComponentUtils.js
+++ /dev/null
@@ -1,22 +0,0 @@
-const instanceSymbol = Symbol('instance');
-
-/**
- * @param {HTMLElement} element
- * @return {import('./BaseComponent').BaseComponent|null}
- */
-export function getComponent(element) {
-  return element[instanceSymbol] || null;
-}
-
-/**
- * Bind the component to the selected element.
- * @param {HTMLElement} element The element to bind the component to.
- * @param {import('./BaseComponent').BaseComponent} instance The component instance.
- */
-export function bindComponent(element, instance) {
-  if (element[instanceSymbol]) {
-    throw new Error('The element is already bound to a component.');
-  }
-
-  element[instanceSymbol] = instance;
-}
diff --git a/src/lib/components/base/component-utils.ts b/src/lib/components/base/component-utils.ts
new file mode 100644
index 0000000..636b8f4
--- /dev/null
+++ b/src/lib/components/base/component-utils.ts
@@ -0,0 +1,29 @@
+import type { BaseComponent } from "$lib/components/base/BaseComponent";
+
+const instanceSymbol = Symbol('instance');
+
+interface ElementWithComponent extends HTMLElement {
+  [instanceSymbol]?: BaseComponent;
+}
+
+/**
+ * Get the component from the element, if there is one.
+ * @param {HTMLElement} element
+ * @return
+ */
+export function getComponent(element: ElementWithComponent): BaseComponent | null {
+  return element[instanceSymbol] || null;
+}
+
+/**
+ * Bind the component to the selected element.
+ * @param element The element to bind the component to.
+ * @param instance The component instance.
+ */
+export function bindComponent(element: ElementWithComponent, instance: BaseComponent): void {
+  if (element[instanceSymbol]) {
+    throw new Error('The element is already bound to a component.');
+  }
+
+  element[instanceSymbol] = instance;
+}
diff --git a/src/lib/extension/ConfigurationController.js b/src/lib/extension/ConfigurationController.ts
similarity index 62%
rename from src/lib/extension/ConfigurationController.js
rename to src/lib/extension/ConfigurationController.ts
index 7f973ff..860b852 100644
--- a/src/lib/extension/ConfigurationController.js
+++ b/src/lib/extension/ConfigurationController.ts
@@ -1,25 +1,24 @@
-import StorageHelper from "$lib/browser/StorageHelper";
+import StorageHelper, { type StorageChangeSubscriber } from "$lib/browser/StorageHelper";
 
 export default class ConfigurationController {
-  /** @type {string} */
-  #configurationName;
+  readonly #configurationName: string;
 
   /**
    * @param {string} configurationName Name of the configuration to work with.
    */
-  constructor(configurationName) {
+  constructor(configurationName: string) {
     this.#configurationName = configurationName;
   }
 
   /**
    * Read the setting with the given name.
    *
-   * @param {string} settingName Setting name.
-   * @param {any} [defaultValue] Default value to return if the setting does not exist. Defaults to `null`.
+   * @param settingName Setting name.
+   * @param [defaultValue] Default value to return if the setting does not exist. Defaults to `null`.
    *
-   * @return {Promise<any|null>} The setting value or the default value if the setting does not exist.
+   * @return The setting value or the default value if the setting does not exist.
    */
-  async readSetting(settingName, defaultValue = null) {
+  async readSetting<Type = any, DefaultType = any>(settingName: string, defaultValue: DefaultType | null = null): Promise<Type | DefaultType> {
     const settings = await ConfigurationController.#storageHelper.read(this.#configurationName, {});
     return settings[settingName] ?? defaultValue;
   }
@@ -27,12 +26,12 @@ export default class ConfigurationController {
   /**
    * Write the given value to the setting.
    *
-   * @param {string} settingName Setting name.
-   * @param {any} value Value to write.
+   * @param settingName Setting name.
+   * @param value Value to write.
    *
    * @return {Promise<void>}
    */
-  async writeSetting(settingName, value) {
+  async writeSetting(settingName: string, value: any): Promise<void> {
     const settings = await ConfigurationController.#storageHelper.read(this.#configurationName, {});
 
     settings[settingName] = value;
@@ -44,10 +43,8 @@ export default class ConfigurationController {
    * Delete the specific setting.
    *
    * @param {string} settingName Setting name to delete.
-   *
-   * @return {Promise<void>}
    */
-  async deleteSetting(settingName) {
+  async deleteSetting(settingName: string): Promise<void> {
     const settings = await ConfigurationController.#storageHelper.read(this.#configurationName, {});
 
     delete settings[settingName];
@@ -63,9 +60,8 @@ export default class ConfigurationController {
    *
    * @return {function(): void} Unsubscribe function.
    */
-  subscribeToChanges(callback) {
-    /** @param {Record<string, StorageChange>} changes */
-    const changesSubscriber = changes => {
+  subscribeToChanges(callback: (record: Record<string, any>) => void): () => void {
+    const subscriber: StorageChangeSubscriber = changes => {
       if (!changes[this.#configurationName]) {
         return;
       }
@@ -73,9 +69,9 @@ export default class ConfigurationController {
       callback(changes[this.#configurationName].newValue);
     }
 
-    ConfigurationController.#storageHelper.subscribe(changesSubscriber);
+    ConfigurationController.#storageHelper.subscribe(subscriber);
 
-    return () => ConfigurationController.#storageHelper.unsubscribe(changesSubscriber);
+    return () => ConfigurationController.#storageHelper.unsubscribe(subscriber);
   }
 
   static #storageHelper = new StorageHelper(chrome.storage.local);
diff --git a/src/lib/extension/EntitiesController.ts b/src/lib/extension/EntitiesController.ts
index da3f950..8a680e5 100644
--- a/src/lib/extension/EntitiesController.ts
+++ b/src/lib/extension/EntitiesController.ts
@@ -1,4 +1,4 @@
-import StorageHelper from "$lib/browser/StorageHelper";
+import StorageHelper, { type StorageChangeSubscriber } from "$lib/browser/StorageHelper";
 import type StorageEntity from "$lib/extension/base/StorageEntity";
 
 export default class EntitiesController {
@@ -71,7 +71,7 @@ export default class EntitiesController {
     /**
      * Watch the changes made to the storage and call the callback when the entity changes.
      */
-    const storageChangesSubscriber = (changes: Record<string, chrome.storage.StorageChange>) => {
+    const subscriber: StorageChangeSubscriber = changes => {
       if (!changes[entityName]) {
         return;
       }
@@ -80,8 +80,8 @@ export default class EntitiesController {
         .then(callback);
     }
 
-    this.#storageHelper.subscribe(storageChangesSubscriber);
+    this.#storageHelper.subscribe(subscriber);
 
-    return () => this.#storageHelper.unsubscribe(storageChangesSubscriber);
+    return () => this.#storageHelper.unsubscribe(subscriber);
   }
 }
diff --git a/src/lib/extension/transporting/validators.js b/src/lib/extension/transporting/validators.js
deleted file mode 100644
index 111c1be..0000000
--- a/src/lib/extension/transporting/validators.js
+++ /dev/null
@@ -1,39 +0,0 @@
-/**
- * Map of validators for each entity. Function should throw the error if validation failed.
- * @type {Map<keyof App.EntityNamesMap|string, ((importedObject: Object) => void)>}
- */
-const entitiesValidators = new Map([
-  ['profiles', importedObject => {
-    if (importedObject.v !== 1) {
-      throw new Error('Unsupported version!');
-    }
-
-    if (
-      !importedObject.id
-      || typeof importedObject.id !== "string"
-      || !importedObject.name
-      || typeof importedObject.name !== "string"
-      || !importedObject.tags
-      || !Array.isArray(importedObject.tags)
-    ) {
-      throw new Error('Invalid profile format detected!');
-    }
-  }]
-])
-
-/**
- * Validate the structure of the entity.
- * @param {Object} importedObject Object imported from JSON.
- * @param {string} entityName Name of the entity to validate. Should be loaded from the entity class.
- * @throws {Error} Error in case validation failed with the reason stored in the message.
- */
-export function validateImportedEntity(importedObject, entityName) {
-  if (!entitiesValidators.has(entityName)) {
-    console.error(`Trying to validate entity without the validator present! Entity name: ${entityName}`);
-    return;
-  }
-
-  entitiesValidators
-    .get(entityName)
-    .call(null, importedObject);
-}
diff --git a/src/lib/extension/transporting/validators.ts b/src/lib/extension/transporting/validators.ts
new file mode 100644
index 0000000..dbb1223
--- /dev/null
+++ b/src/lib/extension/transporting/validators.ts
@@ -0,0 +1,74 @@
+import type StorageEntity from "$lib/extension/base/StorageEntity";
+
+/**
+ * Base information on the object which should be present on every entity.
+ */
+interface BaseImportableObject {
+  /**
+   * Numeric version of the entity for upgrading.
+   */
+  v: number;
+  /**
+   * Unique ID of the entity.
+   */
+  id: string;
+}
+
+/**
+ * Utility type which combines base importable object and the entity type interfaces together. It strips away any types
+ * defined for the properties, since imported object can not be trusted and should be type-checked by the validators.
+ */
+type ImportableObject<EntityType extends StorageEntity> = { [ObjectKey in keyof BaseImportableObject]: any }
+  & { [SettingKey in keyof EntityType["settings"]]: any };
+
+/**
+ * Function for validating the entities.
+ * @todo Probably would be better to replace the throw-catch method with some kind of result-error returning type.
+ *   Errors are only properly definable in the JSDoc.
+ */
+type ValidationFunction<EntityType extends StorageEntity> = (importedObject: ImportableObject<EntityType>) => void;
+
+/**
+ * Mapping of validation functions for all entities present in the extension. Key is a name of entity and value is a
+ * function which throws an error when validation is failed.
+ */
+type EntitiesValidationMap = {
+  [EntityKey in keyof App.EntityNamesMap]?: ValidationFunction<App.EntityNamesMap[EntityKey]>;
+};
+
+/**
+ * Map of validators for each entity. Function should throw the error if validation failed.
+ */
+const entitiesValidators: EntitiesValidationMap = {
+  profiles: importedObject => {
+    if (importedObject.v !== 1) {
+      throw new Error('Unsupported version!');
+    }
+
+    if (
+      !importedObject.id
+      || typeof importedObject.id !== "string"
+      || !importedObject.name
+      || typeof importedObject.name !== "string"
+      || !importedObject.tags
+      || !Array.isArray(importedObject.tags)
+    ) {
+      throw new Error('Invalid profile format detected!');
+    }
+  }
+};
+
+/**
+ * Validate the structure of the entity.
+ * @param importedObject Object imported from JSON.
+ * @param entityName Name of the entity to validate. Should be loaded from the entity class.
+ * @throws {Error} Error in case validation failed with the reason stored in the message.
+ */
+export function validateImportedEntity(importedObject: any, entityName: string) {
+  if (!entitiesValidators.hasOwnProperty(entityName)) {
+    console.error(`Trying to validate entity without the validator present! Entity name: ${entityName}`);
+    return;
+  }
+
+  entitiesValidators[entityName as keyof EntitiesValidationMap]!.call(null, importedObject);
+}
diff --git a/src/lib/utils.js b/src/lib/utils.ts
similarity index 56%
rename from src/lib/utils.js
rename to src/lib/utils.ts
index c7a6531..251fd43 100644
--- a/src/lib/utils.js
+++ b/src/lib/utils.ts
@@ -1,13 +1,13 @@
 /**
  * Traverse and find the object using the key path.
- * @param {Object} targetObject Target object to traverse into.
- * @param {string[]} path Path of keys to traverse deep into the object.
- * @return {Object|null} Resulting object or null if nothing found (or target entry is not an object.
+ * @param targetObject Target object to traverse into.
+ * @param path Path of keys to traverse deep into the object.
+ * @return Resulting object or null if nothing found (or target entry is not an object).
  */
-export function findDeepObject(targetObject, path) {
+export function findDeepObject(targetObject: Record<string, any>, path: string[]): Object|null {
   let result = targetObject;
 
-  for (let key of path) {
+  for (const key of path) {
     if (!result || typeof result !== 'object') {
       return null;
     }
@@ -27,17 +27,15 @@ export function findDeepObject(targetObject, path) {
  *
  * Gathered from right here: https://stackoverflow.com/a/3561711/16048617. Because I don't want to introduce some
  * library for that.
- *
- * @type {RegExp}
  */
-const unsafeRegExpCharacters = /[/\-\\^$*+?.()|[\]{}]/g;
+const unsafeRegExpCharacters: RegExp = /[/\-\\^$*+?.()|[\]{}]/g;
 
 /**
  * Escape all the RegExp syntax-related characters in the following value.
- * @param {string} value Original value.
- * @return {string} Resulting value with all needed characters escaped.
+ * @param value Original value.
+ * @return Resulting value with all needed characters escaped.
  */
-export function escapeRegExp(value) {
+export function escapeRegExp(value: string): string {
   unsafeRegExpCharacters.lastIndex = 0;
   return value.replace(unsafeRegExpCharacters, "\\$&");
 }