Hopper by Hypercubic

Hopper is an agentic development environment for mainframe teams working with COBOL and z/OS systems. Instead of treating legacy environments like normal repositories, it gives agents access to mainframe-native workflows such as TN3270, datasets, JCL, JES output, CICS, VSAM, and return-code analysis while keeping human approval in the loop.

• Mainframe-aware agent actions — navigate TN3270, inspect datasets, write JCL, debug jobs, and query VSAM • Job debugging — decode JESMSGLG, JESYSMSG, SYSUDUMP, abend codes, failing steps, and source lines • Real terminal fallback — includes a TN3270 terminal with PF, PA, and attention-key support • Approval controls — pauses for approval before changes • Free hobby tier — desktop app for macOS, Windows, and Linux, with enterprise SSO/on-prem options

Best for enterprises modernizing COBOL and mainframe workflows without pretending those systems behave like modern cloud apps.