Lazarus is a free cross-platform visual integrated development environment (IDE) for rapid application development (RAD) using the Free Pascal compiler, which supports dialects of Object Pascal, to varying degrees.
License: Open Source
RAD Studio is a comprehensive development environment with a focus on mobile and desktop applications, featuring advanced debugging tools and a rich component library, but it comes with a high cost. In contrast, Lazarus is a free and lightweight alternative suitable for cross-platform desktop development, though it lacks some of the advanced features and mobile support that RAD Studio offers.