All data collection can take place offline, both with KoBoCollect and with Web Forms.
When a user enters data it is stored first on the device. KoBoCollect can be set to attempt sending the information through a network connection immediately or only at a later stage when the interviewer or supervisor wants to upload finalized forms. Web Forms will always attempt to upload data immediately and will retry until a connection has been established again.
All synchronization is proofed even against poor Internet connection quality. Should a connection time out or be interrupted while a specific form is being transferred, it will be resent with the next upload attempt. The server will not integrate half received data in this case. Only when a record has been uploaded successfully and the server confirms receipt will the survey data be removed from the upload queue.
Web Forms uses the browser's HTML5 offline storage to store survey responses as well as the form itself. It is important to wait for the small confirmation message in the top-right on the form, which will show a green checkmark once the form has been cached. After this the form can be accessed and data can be entered even without any connection. It is recommended to create a bookmark on the device to easily access specific forms
What do I do if I have NO access to the internet?
If it is not possible to connect a handset to the Internet at all (the interviewers can't move into an area where a connection is available), then it is also possible to transfer survey data from KoBoCollect through an external tool (ODK Briefcase) and by connecting the mobile devices by USB cable to a local computer. For more details about how to use ODK Briefcase to transfer data, read this post. After this is it possible to upload the survey data from a centralized computer to the KoBoToolbox server, using the same tool.
Finally, it is also possible to install KoBoToolbox on a local computer, e.g. a laptop, and then connect local mobile devices through a local WiFi to the computer. This WiFi does not need to be connected to the Internet as there would be a direct connection between the mobile devices and the local computer. See here for finding out how to install KoBoToolbox on your computer.