There are several ways to fund startup app ideas, including bootstrapping, seeking angel investors, crowdfunding, or applying for startup incubators. Bootstrapping involves using personal funds to get the app off the ground. Angel investors can provide seed funding in exchange for equity. Platforms like Kickstarter allow you to raise money from potential users in exchange for early access or other incentives. Startup incubators or accelerators offer mentorship, networking, and funding to help bring your app to market.