GnuCash is not available as a web app but there are plenty of alternatives that runs in the browser with similar functionality. The best Online alternative is Mint.com, which is free. If that doesn't suit you, our users have ranked more than 100 alternatives to GnuCash and loads of them are available as a web app so hopefully you can find a suitable replacement. Other interesting Online alternatives to GnuCash are Akaunting (Freemium, Open Source), Manager (Freemium), Buxfer (Freemium) and Zenmoney (Freemium).
Kualto is a personal finance management application that takes a balance forecasting approach to budgeting. It allows for navigating to any week in the future and seeing your expected account balance based on estimated expenses and income.
Manage your personal finances online. Organize your financial life, categorize your spendings and incomes. Visualize your cash flow. Begin to control your money — your financial information will be available from anywhere!
Never forget about a subscription renewal again. Save money by cancelling unused subscriptions. Renegotiate in time. Other financial features such as expense tracking are available as well. Reporting is simple but being developed over time.