Question: Can you suggest a tool that allows me to build responsive mobile apps with a visual drag-and-drop interface?

If you want to build mobile apps that respond to different screen sizes with a visual drag-and-drop interface, FlutterFlow is a great option. This web-based tool lets developers build modern apps with Firebase integration, API support and other features like a UI builder with 80+ Flutter widgets, 170 pre-built components and real-time collaboration. It has several pricing levels, including a free option, so it's good for small projects and teams.

Another option is Bubble, a full-stack no-code app builder that uses AI to help you design and deploy production-ready apps. With a drag-and-drop editor, hundreds of customizable templates, and scalable and secure hosting, Bubble is good for everything from startups to enterprise-scale projects. It's got collaboration tools for up to 40 real-time contributors, and you can choose from several pricing plans, including a free development version.

Nowa is another powerful tool for building high-quality mobile, web and desktop apps with a visual design interface. It lets you add custom logic and link to different backends without having to write any code, so it's good for developers and teams. Nowa has a drag-and-drop interface for designing responsive apps and can export to multiple platforms with one click, collaborate with others and get premium support. It's got a range of pricing levels, including a free option.

For a low-code approach, Backendless offers a full suite of tools to build high-performance apps. That includes a visual UI builder, codeless logic and direct API integration for managing data. Backendless offers responsive apps for web and mobile, and its real-time database lets you handle things like live updates and chat. It's got user management tools and flexible deployment options, from a free plan to more advanced paid tiers.