Overview

The Local Runner — surfaced in the app as the Shift-Left Agent — is a small desktop agent that runs API tests on your own machine and reports results back to the platform. Use it when tests must reach endpoints the central engine can't: private networks, internal services, or localhost. It runs a local HTTP server on 127.0.0.1:5004 and is selected per run as the Shift-Left Agent execution mode. Explore the related capability at shift-left agent.

Availability: all editions.

Before you begin

Any signed-in user can check status, install, start, stop, and select the runner — there's no separate edition gate. Test execution itself still respects your license status.
The runner listens only on the loopback address 127.0.0.1:5004, so it's reachable from your machine, not the network.
Keep it running while local executions are in progress; if it's down, local runs can't complete.

Step 1 — Find the runner controls

The runner status and controls appear inline on the Execution Mode selector wherever you launch a run (for example in the Test Workbench and when starting a workflow). You'll see two cards:

Shift-Left Engine — runs tests on the server; labeled Always Available.
Shift-Left Agent — the Local Runner. Its card shows a live status line and small action buttons.

The status line reads one of:

Available (green check) — the runner is up; the card also shows its Version.
Not Running (warning icon) — the runner isn't responding on 127.0.0.1:5004.
Checking… — a status check is in progress.

Step 2 — Check, start, and stop the runner

On the Shift-Left Agent card, the small icon buttons do the following:

Control	What it does
Start (play icon)	Shown when the runner is Not Running. Launches the agent; it comes up on `127.0.0.1:5004`. If it's already running, the app reports it's already up.
Stop (stop icon)	Shown when the runner is Available. Shuts the agent down (gracefully first, then by stopping the process).
Refresh status (circular-arrow icon)	Re-checks whether the runner is responding and updates the status line.
Open status (open-in-new-tab icon)	Opens `http://127.0.0.1:5004/status` in a new tab so you can see the runner's raw health JSON.

Step 3 — Install the runner

If the runner has never been set up on this machine, install it before starting:

From the app, the Install action installs the agent's dependencies and registers it globally on your machine.
You can also install it outside the app using its bundled installer/executable (Windows, macOS Intel, and macOS Apple Silicon builds are provided).

Once installed, use Start (Step 2) to bring it up.

Step 4 — Run tests on the Local Runner

On the Execution Mode selector, choose the Shift-Left Agent card (its description reads "Execute tests locally. Best for development and private APIs.").
Confirm the status line shows Available — if not, click Start and then Refresh status.
Launch your test or workflow as usual. Execution runs on your machine and results report back to the platform.
Keep the runner running until the execution finishes.

For CI/CD and scheduled runs, use Shift-Left Engine instead; the Local Runner is for reaching endpoints only your machine can see.

Troubleshooting / Notes

Status stays "Not Running" after Start — give it a moment and click Refresh status; the app waits for the agent to come up on port 5004 before confirming. If it still fails, the local-runner directory or its entry point may be missing on the host — reinstall (Step 3).
Port 5004 in use — another process may hold the port; stop it, or stop and restart the runner.
Local runs blocked — check the runner's license status via Open status; an expired or invalid backend license can block execution.
The runner is loopback-only (127.0.0.1:5004) and can't be reached from other machines by design.

Local Runner