Why can't I sign in with Google inside TikTok or Instagram?
Because Google does not allow its sign-in page to run inside an app's built-in browser, which is what opens when you tap a link in TikTok or Instagram[1]. The fix is to open the same link in your phone's real browser (Safari, Chrome or another) and sign in there, or to use a site that does not need Google sign-in.
What is going on
When you tap a link in TikTok or Instagram, the page usually opens in a browser built into the app, not in Safari or Chrome. Technically this is an embedded browser, often called a webview, and the app that hosts it controls it.
Google's OAuth policies say developers must not send Google sign-in requests to an embedded browser under their control[1]. Google started blocking sign-in in all embedded webviews on 2021-09-30[2]. The security concern is simple: an app that hosts an embedded browser can, in principle, read what is typed into it. Your phone's own browser keeps the password out of the app's reach.
What the disallowed_useragent error means
If you tap 'Sign in with Google' inside an in-app browser, you may see an error page mentioning disallowed_useragent. Google's documentation says this means the sign-in page was opened in an embedded browser that its policies do not allow, including when an app opens a general web link in an embedded browser[3]. Nothing is wrong with your Google account, and trying again in the same place will give the same error.
How to fix it
- Open the link in your real browser. In the in-app browser, look for the menu (usually three dots, often at the top right) or a share button. Most versions offer an option along the lines of 'Open in browser', 'Open in Chrome' or 'Open in Safari'. Labels differ by app, phone and app version; we found no official TikTok or Instagram help page for these steps, only third-party how-tos.
- Or copy the link and paste it. If you cannot find that option, use 'Copy link' from the same menu or the share sheet, then paste it into Safari or Chrome.
- Sign in there. Google sign-in works normally in your phone's own browser.
- Or skip Google sign-in. Many sites offer email sign-in or a guest mode that works inside the in-app browser.
Our step-by-step page how to open a TikTok link in your real browser covers the menus in more detail, including what to do when there is no 'open in browser' option.
Why this matters for websites you open from TikTok
A site built for a TikTok audience has to hide Google sign-in in the in-app browser or offer another way in. We hit this ourselves: most people reach Cast from a TikTok or Instagram post, so Cast does not ask you to sign in at all. Your first tap creates a guest account in that browser, and you can make your first video right there. Google sign-in only appears when you open Cast in a regular browser.
Google's developer docs recommend that apps open general links in the phone's default browser instead[4]. Whether an app does that is up to the app.
Where Cast fits
- You opened a Cast link inside TikTok or Instagram and want to make a video without signing in: a guest account is created on your first tap.
- You want your first 5-second video free, with no email and no card, from inside the app.
Where it does not:
- Moving your guest videos to another browser: a guest account lives in the browser where you made it. Google sign-in is blocked inside TikTok and Instagram, so you cannot attach them to a Google account from there.
- Fixing sign-in on other websites: for those, open the link in your real browser.
People also ask
- Is my Google account blocked?
- No. The block applies to the in-app browser, not your account. The same sign-in works in Safari or Chrome.
- Does this happen in Facebook, Snapchat and other apps too?
- Yes, in any app that opens links in its own embedded browser, because Google blocks its sign-in in all embedded webviews[2].
- Can I turn off TikTok's in-app browser?
- We could not find an official TikTok setting for it. The reliable route is opening each link in your browser from the menu or by copying the link.
- Does email sign-in still work in an in-app browser?
- Usually. The rule covers Google sign-in; an email and password or a one-time code generally works. A magic sign-in link sent by email will open in your mail app or browser, not back inside TikTok, so finish signing in there.
Sources
Claims about other companies come from their own pages, read on the date shown. Products and prices change; check the link for the current version.
- Google Identity: OAuth 2.0 policies (read )
- Google Developers Blog: upcoming security changes to Google's OAuth 2.0 authorization endpoint (read )
- Google Identity: OAuth 2.0 for mobile and desktop apps (disallowed_useragent) (read )
- Google Identity: OAuth 2.0 for mobile and desktop apps (webview guidance) (read )
Related answers
- How do I open a link from TikTok in my real browser?
- Why does a website not work inside TikTok's or Instagram's browser?
- Is there a free AI video generator with no sign-up and no watermark?
- What is the best free AI video app for my phone?
Part of the Cast answers library (In-app browser problems).
Updated