Every other question I’ve read is asking how to bypass or workaround Google’s policy that prevents access from embedded web views; I want to comply but I want to help my users.

I have a web based application (no native app involved) which redirects to Google Auth and back to the website – I don’t want to use the JavaScript solution for various reasons, and generally this approach works really well.

I recently got a support request from a user who had received the disallowed_useragent error. After hours of research I eventually discovered they had been sent a link to my app in Facebook Messenger, clicked it and tried to login within the messengers webview; which obviously failed.

I would like to display users in this position a message, telling them to try a real browser – but how can I detect the user agent is on Google’s disallow list?

Thanks.