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3270Web

The modern browser client for IBM 3270 mainframe sessions — with AI-driven automation, chaos exploration, workflow recording, and a full REST API.

No emulator install. No thick client. Open a browser tab, connect to any TN3270 host, and work exactly like you would at a real 3270 terminal — then let the automation features do the heavy lifting.

Feature Highlights

  • AI Chat Mode

    Drive any 3270 session by typing plain English. The AI reads the current screen, proposes field fills and key presses, and waits for your approval before acting. Toggle Auto Mode to let it run hands-free.

    AI Chat Mode

  • Chaos Exploration

    Auto-discover every navigation path on a host. Chaos mode fills fields with generated values, presses AID keys, and records every screen transition — then exports a reusable workflow JSON ready for load testing with 3270Connect.

    Chaos Mode

  • Workflow Recording & Playback

    Capture terminal actions as portable JSON. Replay them with a single click, step through them one action at a time in debug mode, or hand the file to any CI pipeline.

    Recordings and Playback

  • REST API

    Connect, read screens, submit input, and control chaos runs over HTTP. Wire 3270 sessions into any automation stack — scripts, pipelines, or custom tooling.

    REST API

  • Host Compatibility Profiler

    Probe any TN3270 host and capture its negotiated terminal model, protocol options, capabilities, and timing as a JSON document. Same schema as 3270Connect -profile, so profiles diff cleanly across tools and environments.

    Host Compatibility Profiler

  • Chaos Mind-Map Compare

    Diff two previously-exported chaos mind maps to surface field and transition divergence between hosts — ideal for migration-readiness checks against Rocket Enterprise Server stand-ins.

    Chaos Mind-Map Compare

  • IBM 3270 Terminal Fonts

    Three bundled 3270-style web fonts (Regular, Semi-Condensed, Condensed) make the browser session look like a real 3279 display on any platform — no install, no CDN fetch.

    Terminal Fonts

Screenshots

Connect screen Session screen Logging screen Sample app

First Session

  1. Get 3270Web running — native Linux binary, Docker, or Docker Compose.
  2. Open 3270Web in your browser (http://localhost:8080).
  3. Enter your TN3270 host and port on the connect screen.
  4. Use the terminal — keyboard shortcuts, PF keys, and field navigation all work as expected.
  5. Optional: hit Start recording to capture the session for replay later.

Install and Run    Full setup guide

What's in This Guide

Section What you'll find
Install and Run Run the native Linux binary, Docker image, or Docker Compose
Connect and Use 3270Web Host configuration, startup options, UI tour
Recordings and Playback Record, load, play, debug, and export workflows
Chaos Mode Automated screen exploration and load-test export
AI Chat Mode Conversational session control via GitHub Copilot
Keyboard and Controls Full keyboard shortcut reference
Screen Size and Model Guide 3270 model limits and field size rules
REST API Endpoint reference for scripting and CI
Host Compatibility Profiler Probe a host once and capture its CompatibilityProfile JSON for cross-environment comparison
Chaos Mind-Map Compare Diff two exported mind maps to surface divergence between hosts
Terminal Fonts Bundled IBM 3270-style web fonts and how to switch between them
Compatibility Profile Schema Field-by-field reference for the shared profile JSON (v1.0.0)
Feature Roadmap Planned and in-progress features