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Open source · v2.0.0

Replay the mainframe at any scale

Replay repetitive mainframe tasks, check regression workflows in CI, and measure your host under load. Start with a local sample lab — no mainframe needed. Export recordings from 3270Web or write a JSON workflow, then replay it with 3270Connect.

Try the sample lab Install for my host

Free and open source. Runs locally. Docker is required for the sample lab. Watch the demo.

session · load run 25 workers 
$ 3270Connect -config workflow.json \
    -concurrent 25 -runtime 60 -headless
› connect  mvs.example.com:992    [ok]
› workers  25 spawned               [live]
› steps    FillString · PressEnter  [ok]
› metrics  :9090/metrics scraped    [up]
›
ReplayJSONWorkflows you can review
AutomationCIExit status reflects the result
Host scaleLoadConfigurable concurrency
EmulatorBundledNo separate emulator install

See it work

The operations console: launching an eight-worker load run from the browser, then watching the process table, the live screen flow and the charts fill in.

Shorter walk-throughs of one thing at a time:

Video Where
Your first workflow — describe a session in JSON and replay it Basic Usage
Run it at scale — -concurrent and -runtime Basic Usage
Call it over HTTP — one POST returns the screen Advanced Features
The operations console, end to end Web Dashboard
Sign-in and administration with AUTH_MODE=local Accounts and Sign-In
Profile a host before you trust a workflow against it Host Compatibility Profiler
Drive it from an AI client over MCP MCP Server

What it does

  • Workflows as JSON

    Describe a session once — connect, fill, press, assert, grab the screen, disconnect — and run it anywhere. No scripting language to learn, no emulator to install.

    Workflow actions

  • Concurrency & load testing

    Run the same workflow across hundreds of parallel workers for a fixed duration, with per-workflow timeouts, grace periods and a controlled shutdown.

    Basic usage

  • Live operations console

    Watch runs as they happen: latency percentiles, outcomes, per-process controls and streaming logs — served straight from the binary, no external services.

    Web dashboard

  • Accounts when you need them

    One operator needs no sign-in and gets none. Share the port and AUTH_MODE=local adds accounts, groups, per-account API tokens, single sign-on and an audit trail of who aimed what at which host.

    Accounts and sign-in

  • Prometheus metrics

    Scrape tn3270_connect_seconds, tn3270_step_seconds, workflow outcomes and live worker counts from -promListen and put mainframe runs on the same board as everything else.

    Metrics & monitoring

  • AI Chat mode

    Drive a live session from 3270Web by typing plain English. The model reads the screen, proposes field fills and key presses, and waits for your approval before acting.

    AI Chat mode

  • Host compatibility profiler

    Probe a host once with -profile and write a CompatibilityProfile JSON document that diffs cleanly against 3270Web output across environments.

    Host profiler

The operations console

The 3270Connect operations console

The web dashboard — live workflow metrics, latency percentiles, per-process controls and log streaming, served straight from the binary.

Start with one successful replay

  1. Try the Docker lab with its bundled host and workflow, or install the binary.
  2. Open the console and choose Try a sample replay, or follow the first CLI replay.
  3. Check the completed result and screen captures before creating a load test for your own host.

Try the sample lab

Platform support and prerequisites · Source and licence