# Component-Based Development Component-based development builds applications from reusable, independently testable controls and services with declared interfaces. The Delphi/VCL ecosystem in Bryant's software history—rich editors, grids, spelling, regex, HTML, networking, database, compression, and update components—is a clear historical component platform. The same instinct later appears as Perl modules, X capabilities, npm packages, Vue components, and agent tools. Related: [[wiki/Rapid Application Development|Rapid Application Development]], [[wiki/Capability-Oriented Architecture|Capability-Oriented Architecture]], [[projects/Software I've Bought and Used Over the Years|Software Toolchain]].