Dev UI & CLI

Genkit provides a developer UI and CLI for testing, debugging, and inspecting your AI logic.

Installing the CLI

npm install -g genkit

Starting the Dev UI

Run your application with the Genkit CLI to launch the developer UI:

genkit start -- ./run.sh
# Or:
genkit start -- mvn exec:java

The Dev UI launches at http://localhost:4000 by default.

What the Dev UI provides

• List all registered actions — Flows, models, tools, prompts, retrievers, evaluators
• Run actions with test inputs — Execute flows interactively
• View traces — Inspect execution logs with full span details
• Manage datasets — Create and manage evaluation datasets
• Run evaluations — Execute evaluators and review results

Reflection server

When running in dev mode (devMode(true)), Genkit starts a reflection server on port 3100 (configurable via reflectionPort()). The Dev UI connects to this server.

Genkit genkit = Genkit.builder()
    .options(GenkitOptions.builder()
        .devMode(true)
        .reflectionPort(3100)  // Default port
        .build())
    .build();

Running flows from the CLI

# Run a flow
genkit flow:run tellJoke '"pirates"'

# Run with streaming output
genkit flow:run tellJoke '"pirates"' -s