FireJournal is an iOS application, or app. It doesn't need a browser to run. Some software applications look like they are designed for tablet devices, but require Internet access to operate.
FireJournal is a "local" app, meaning it will run perfectly without any connectivity to the Internet. Certain functions will not work without Internet connectivity, such as auto-population of an address in a report, journal entry, or form. However, you as the user always have manual control to add whatever you need.