Hopper: Agentic TN3270 Terminal

Hopper is a desktop application for z/OS engineers that bundles a TN3270 terminal, a datasets browser, a jobs browser and an AI agent into a single interface. In natural language, you can ask the AI Agent to read COBOL source, submit and monitor batch jobs, decode VSAM records and write changes under your supervision. Hopper runs on macOS, Windows and Linux.

Hopper runs on macOS, Windows and Linux. Hopper provides separate builds for Apple Silicon and Intel processors on macOS. On Windows, Hopper provides an x64 installer. On Linux, Hopper supports Debian and Ubuntu via a .deb package and any Linux distribution via an AppImage.

No. Hopper runs entirely on your laptop and requires no mainframe-side installation. Nothing runs on z/OS, so your sysprog does not need to deploy anything. Hopper connects to your mainframe over standard TN3270 and optional FTP protocols using your existing network connection.

Hopper connects to z/OS using two standard mainframe protocols: TN3270 for the live terminal session and FTP for datasets and the JES queue. TN3270 is required. FTP is optional but recommended; without FTP credentials, the datasets browser, jobs browser, builds and most agent tools stay disabled.

Hopper's AI agent reads COBOL and JCL source, submits and monitors jobs, decodes VSAM records and drives ISPF using plain English prompts. The agent operates across six tool categories spanning datasets, jobs, terminal, CICS, COBOL and data taps, and can chain work across subsystems in a single conversation turn.

Hopper's datasets tools list, read, write and allocate sequential datasets, PDSes and members.

Hopper's jobs tools submit JCL, wait for completion, read spool output and classify failures.

Hopper's terminal tools drive the TN3270 session, read screens and send keystrokes and attention keys.

CICS operations in Hopper include sign-on, transaction execution, resource installation and CEDA defines.

COBOL support in Hopper covers compilation, copybook parsing and VSAM record decoding.

Hopper's data tap tools snapshot VSAM data into a queryable local copy and run SQL against it.

Hopper's AI agent handles COBOL, JCL, REXX and CLIST. The agent traces how programs and datasets connect and works out what to edit for the task you describe. The agent reads the source directly from your PDSes and uses it within the current conversation.

Hopper's approval model separates read-only actions from mutating actions. Read-only actions such as listing members, reading source or querying spool run instantly without confirmation. Mutating actions such as writing a member, submitting a job or installing a CICS resource pause in chat for your explicit approval before anything on the mainframe changes.

Hopper stores FTP and CICS credentials in your operating system keychain, not in the application itself. Hopper replaces hidden fields on TN3270 screens, including passwords, with placeholders before screen content reaches the AI agent. The agent never sees raw credentials, and no credentials appear in chat history or exported conversation files.

Hopper is an AI-powered mainframe workspace that helps teams work faster in the systems they already operate. It supports day-to-day mainframe operations as well as modernization work by making it easier to navigate terminal screens, find and inspect applications, understand programs and job flows, and retrieve the information needed to take the next action.

Instead of manually moving through TN3270 screens, commands, and legacy workflows, teams can use agents to navigate the environment and surface relevant context. Hopper does not replace the mainframe or perform the modernization itself. It helps operators, developers, and modernization teams move through familiar and unfamiliar systems much faster while maintaining control over the underlying environment.

Hopper offers a free Hobby tier that requires no credit card and includes all core features. Hypercubic offers an Enterprise tier with custom pricing for organizations that need SAML SSO, MCP Server Access, admin and model controls, org-wide privacy controls, no model training, priority support, on-premises or VPC deployment and SOC 2 and penetration test reports.