TempBuddy allows you to check-in and check-out even when you don't have internet connectivity on the device. The time logs are synced to the server once the device is online again.
Two important points to note while using offline checks -
i) You should already be logged into the App while you have internet connection on the device. Like any App, it would only allow you to be in the App and see the option to check in/out only if you are already logged in
ii) You should inform the agency that you are using the offline check feature for the day so that the agency does not duplicate the check in/out entry (since your check in/out is offline, it will not show the time logs on the recruiter's side until the device is online again)