diff --git a/ext/src/_locales/en/messages.json b/ext/src/_locales/en/messages.json
index d4e51c8..da775dd 100755
--- a/ext/src/_locales/en/messages.json
+++ b/ext/src/_locales/en/messages.json
@@ -346,6 +346,14 @@
         "message": "Custom",
         "description": "Default <option> for knownApps <select>."
     },
+    "optionsSiteWhitelistCustomUserAgent": {
+        "message": "Custom user agent:",
+        "description": "Custom user agent option label."
+    },
+    "optionsSiteWhitelistCustomUserAgentDescription": {
+        "message": "If specified, a custom user agent string to use for whitelisted sites.",
+        "description": "Custom user agent option description."
+    },
 
     "optionsMirroringCategoryName": {
         "message": "Screen/tab casting",
diff --git a/ext/src/background/whitelist.ts b/ext/src/background/whitelist.ts
index 5d22ef2..9dc3cf6 100644
--- a/ext/src/background/whitelist.ts
+++ b/ext/src/background/whitelist.ts
@@ -33,6 +33,8 @@ let platform: string;
 let chromeUserAgent: string | undefined;
 let chromeUserAgentHybrid: string | undefined;
 
+let customUserAgent: string | undefined;
+
 export async function initWhitelist() {
     logger.info("init (whitelist)");
 
@@ -42,6 +44,8 @@ export async function initWhitelist() {
         chromeUserAgent = getChromeUserAgent(platform);
         chromeUserAgentHybrid = getChromeUserAgent(platform, true);
 
+        customUserAgent = await options.get("siteWhitelistCustomUserAgent");
+
         /**
          * If a UA string can't be obtained, don't bother continuing
          * extension initialization
@@ -55,9 +59,13 @@ export async function initWhitelist() {
     await registerSiteWhitelist();
 
     // Re-register when options change
-    options.addEventListener("changed", ev => {
+    options.addEventListener("changed", async ev => {
         const alteredOpts = ev.detail;
 
+        if (alteredOpts.includes("siteWhitelistCustomUserAgent")) {
+            customUserAgent = await options.get("siteWhitelistCustomUserAgent");
+        }
+
         if (
             alteredOpts.includes("siteWhitelist") ||
             alteredOpts.includes("siteWhitelistEnabled")
@@ -92,9 +100,10 @@ async function onWhitelistedBeforeSendHeaders(
     for (const header of details.requestHeaders) {
         if (header.name === "User-Agent") {
             header.value =
-                host?.value === "www.youtube.com"
+                customUserAgent ||
+                (host?.value === "www.youtube.com"
                     ? chromeUserAgentHybrid
-                    : chromeUserAgent;
+                    : chromeUserAgent);
             break;
         }
     }
@@ -126,9 +135,10 @@ function onWhitelistedChildBeforeSendHeaders(
             for (const header of details.requestHeaders) {
                 if (header.name === "User-Agent") {
                     header.value =
-                        host?.value === "www.youtube.com"
+                        customUserAgent ||
+                        (host?.value === "www.youtube.com"
                             ? chromeUserAgentHybrid
-                            : chromeUserAgent;
+                            : chromeUserAgent);
                     break;
                 }
             }
diff --git a/ext/src/defaultOptions.ts b/ext/src/defaultOptions.ts
index cd03d25..8eb2fbe 100644
--- a/ext/src/defaultOptions.ts
+++ b/ext/src/defaultOptions.ts
@@ -1,6 +1,27 @@
 "use strict";
 
-import { Options } from "./lib/options";
+import type { WhitelistItemData } from "./background/whitelist";
+
+export interface Options {
+    bridgeApplicationName: string;
+    bridgeBackupEnabled: boolean;
+    bridgeBackupHost: string;
+    bridgeBackupPort: number;
+    mediaEnabled: boolean;
+    mediaSyncElement: boolean;
+    mediaStopOnUnload: boolean;
+    localMediaEnabled: boolean;
+    localMediaServerPort: number;
+    mirroringEnabled: boolean;
+    mirroringAppId: string;
+    receiverSelectorCloseIfFocusLost: boolean;
+    receiverSelectorWaitForConnection: boolean;
+    siteWhitelistEnabled: boolean;
+    siteWhitelist: WhitelistItemData[];
+    siteWhitelistCustomUserAgent: string;
+
+    [key: string]: Options[keyof Options];
+}
 
 export default {
     bridgeApplicationName: BRIDGE_NAME,
@@ -17,5 +38,6 @@ export default {
     receiverSelectorCloseIfFocusLost: true,
     receiverSelectorWaitForConnection: true,
     siteWhitelistEnabled: true,
-    siteWhitelist: [{ pattern: "https://www.netflix.com/*" }]
+    siteWhitelist: [{ pattern: "https://www.netflix.com/*" }],
+    siteWhitelistCustomUserAgent: ""
 } as Options;
diff --git a/ext/src/lib/options.ts b/ext/src/lib/options.ts
index fdf0955..68c9316 100644
--- a/ext/src/lib/options.ts
+++ b/ext/src/lib/options.ts
@@ -1,7 +1,7 @@
 "use strict";
 
-import defaultOptions from "../defaultOptions";
-import type { WhitelistItemData } from "../background/whitelist";
+import defaultOptions, { Options } from "../defaultOptions";
+export { Options };
 
 import logger from "./logger";
 
@@ -12,26 +12,6 @@ const storageArea = new TypedStorageArea<{
     options: Options;
 }>(browser.storage.sync);
 
-export interface Options {
-    bridgeApplicationName: string;
-    bridgeBackupEnabled: boolean;
-    bridgeBackupHost: string;
-    bridgeBackupPort: number;
-    mediaEnabled: boolean;
-    mediaSyncElement: boolean;
-    mediaStopOnUnload: boolean;
-    localMediaEnabled: boolean;
-    localMediaServerPort: number;
-    mirroringEnabled: boolean;
-    mirroringAppId: string;
-    receiverSelectorCloseIfFocusLost: boolean;
-    receiverSelectorWaitForConnection: boolean;
-    siteWhitelistEnabled: boolean;
-    siteWhitelist: WhitelistItemData[];
-
-    [key: string]: Options[keyof Options];
-}
-
 interface EventMap {
     changed: Array<keyof Options>;
 }
diff --git a/ext/src/ui/options/Options.svelte b/ext/src/ui/options/Options.svelte
index b168602..c54881a 100644
--- a/ext/src/ui/options/Options.svelte
+++ b/ext/src/ui/options/Options.svelte
@@ -10,14 +10,20 @@
     import options, { Options } from "../../lib/options";
     import defaultOptions from "../../defaultOptions";
 
+    import { getChromeUserAgent } from "../../lib/userAgents";
+
     const _ = browser.i18n.getMessage;
 
     let formElement: HTMLFormElement;
     let isFormValid = true;
     let showSavedIndicator = false;
 
+    let platform: string;
+
     let opts: Options | undefined;
     onMount(async () => {
+        platform = (await browser.runtime.getPlatformInfo()).os;
+
         opts = await options.getAll();
         options.addEventListener("changed", async () => {
             opts = await options.getAll();
@@ -277,6 +283,23 @@
                 </div>
             </div>
 
+            <div class="option">
+                <label class="option__label" for="siteWhitelistCustomUserAgent">
+                    {_("optionsSiteWhitelistCustomUserAgent")}
+                </label>
+                <div class="option__control">
+                    <input
+                        type="text"
+                        class="user-agent-string-custom"
+                        bind:value={opts.siteWhitelistCustomUserAgent}
+                        placeholder={getChromeUserAgent(platform)}
+                    />
+                    <div class="option__description">
+                        {_("optionsSiteWhitelistCustomUserAgentDescription")}
+                    </div>
+                </div>
+            </div>
+
             <div class="option">
                 <div class="option__label">
                     {_("optionsSiteWhitelistContent")}
diff --git a/ext/src/ui/options/styles/index.css b/ext/src/ui/options/styles/index.css
index abe033d..f8d4652 100644
--- a/ext/src/ui/options/styles/index.css
+++ b/ext/src/ui/options/styles/index.css
@@ -20,10 +20,15 @@ body {
     font-size: 13px;
 }
 
-a              { color: var(--blue-40); }
-a:hover        { color: var(--blue-50); }
-a:hover:active { color: var(--blue-60); }
-
+a {
+    color: var(--blue-40);
+}
+a:hover {
+    color: var(--blue-50);
+}
+a:hover:active {
+    color: var(--blue-60);
+}
 
 button.ghost {
     width: 24px !important;
@@ -38,7 +43,6 @@ button.ghost:not(:hover) {
     background-color: initial;
 }
 
-
 #form {
     display: flex;
     flex-direction: column;
@@ -209,7 +213,6 @@ button.ghost:not(:hover) {
     width: 75px;
 }
 
-
 .category {
     border: initial;
     display: grid;
@@ -228,7 +231,6 @@ button.ghost:not(:hover) {
     border-bottom: 1px solid var(--border-color);
 }
 
-
 .category > hr {
     border: initial;
     border-top: 1px solid var(--border-color);
@@ -258,7 +260,6 @@ button.ghost:not(:hover) {
     grid-column: span 2;
 }
 
-
 .option {
     display: contents;
 }
@@ -316,7 +317,6 @@ button.ghost:not(:hover) {
     margin-inline-start: initial;
 }
 
-
 .whitelist {
     background-color: var(--box-background);
     border: 1px solid var(--border-color);
@@ -389,7 +389,6 @@ button.ghost:not(:hover) {
     margin-inline-end: auto;
 }
 
-
 .translator__tag {
     color: #0a84ff;
     display: inline-block;
@@ -400,6 +399,9 @@ button.ghost:not(:hover) {
     vertical-align: text-top;
 }
 
+.user-agent-string-custom {
+    width: -moz-available;
+}
 
 @media (prefers-color-scheme: dark) {
     .whitelist__item:nth-child(even) {