Where should I put my API key: the component or Settings?

In current versions, provider keys are stored once under Settings, then Model Providers. That avoids pasting keys into individual components and makes flows easier to share safely.

What does the Playground do?

It is a built-in chat for testing a flow. It needs a Chat Input and a Chat Output (plus a Language Model or Agent) to work, and it is meant for testing rather than embedding in applications.

Langflow Module 2: Your First Flow with Basic Prompting

Introduction

The fastest way to understand Langflow is to run a working flow. In this module you create a flow from the Basic Prompting template, connect it to a language model provider, test it in the Playground, and change its behavior by editing the prompt.

Prerequisites

Langflow running (Module 1)
An API key from an LLM provider such as OpenAI or Anthropic

Step-by-Step Guide

Step 1: Create the flow from a template

On the Projects page, open a project and click New Flow. Choose the Basic Prompting template. It builds a small flow with four components: Chat Input, Prompt Template, Language Model, and Chat Output.

Step 2: Add your model provider key

Click your profile icon, choose Settings, then Model Providers. Select your provider, enter your key in the API Key field, and click Save. Then enable the specific models you want to use; they will appear in the Language Model component's model list. Only one key per provider can be stored.

Step 3: Select the model

Return to the flow and open the Language Model component. Pick the provider and model you enabled. The component has a Temperature field and a Stream option, and a System Message field that the template connects to the Prompt Template.

Step 4: Test in the Playground

Click Playground and send a message. The Chat Input component passes your text to the Language Model, whose response flows to Chat Output and appears in the chat. If nothing happens, check that a model is selected and the provider key was saved.

Step 5: Change the behavior by editing the prompt

Open the Prompt Template component and edit its text, for example to make the assistant a patient tutor who answers in three short bullet points. Click Check & Save and chat again. Prompts are the cheapest and fastest way to change what a flow does.

You are a patient programming tutor.
Answer every question in at most three short bullet points
and end with one practice exercise.

FAQs

Where should I put my API key: the component or Settings?: In current versions, provider keys are stored once under Settings, then Model Providers. That avoids pasting keys into individual components and makes flows easier to share safely.
What does the Playground do?: It is a built-in chat for testing a flow. It needs a Chat Input and a Chat Output (plus a Language Model or Agent) to work, and it is meant for testing rather than embedding in applications.

Summary

A basic flow is Chat Input, Prompt Template, Language Model, and Chat Output. Save your provider key in Settings, choose a model, test in the Playground, and tune behavior by editing the prompt.