Speclj is a TDD/BDD testing framework for Clojure and ClojureScript that provides a rich DSL for writing specifications. It features a hierarchical component system for organizing tests, cross-platform support via reader conditionals, multiple runners (standard and vigilant), various reporters, stubbing/mocking capabilities, and tag-based test filtering. The architecture is modular with clear separation between test definition (speclj.core), platform abstraction (speclj.platform), test execution (speclj.running), and reporting (speclj.reporting).