Tape/Z (Tools for Assembly Program Exploration for Z/OS)

Tape/Z (Tools for Assembly Program Exploration for Z/OS) is an evolving toolkit for analyzing mainframe HLASM (High-Level Assembler) code. Developed by a Thoughtworker, it provides capabilities such as parsing, control flow graph construction, dependency tracing and flowchart visualization. We’ve long noted the scarcity of open, community-driven tools in the mainframe space, where most options remain proprietary or tied to vendor ecosystems. Tape/Z helps close that gap by offering accessible, scriptable analysis capabilities. Alongside COBOL REKT — a companion toolkit for COBOL that we’ve also used multiple times with clients — it represents encouraging progress toward modern, developer-friendly tooling for mainframe systems.