You do not need to use Quicken on the Web to use Quicken for Windows. Quicken on the Web is a convenient way to use Quicken, but it does not have all of the power and options of Quicken for Windows. You can't add or delete accounts, budgets, renaming rules, or memorized payees. What can’t I do in Quicken on the Web (but can do on the desktop app) You can add and delete transactions, as well as designate categories, tags, notes or other information for transactions. You can view account transactions as well as account totals, spending, budgets, bill & income reminders, and investments.
Be sure to use before and after every session. Information cannot be shared between the apps unless you sync. Always sync Quicken (desktop or web) before and after each session.
When using your desktop Quicken application with Quicken for the Web, the key is synchronization.
It is not designed to be your only Quicken application. Quicken on the Web is a companion to our Quicken desktop applications.