Version: v1.87

# HOPR Apps - Hello world

The following is a 5-minutes guide for you to get familiar with the HOPR protocol and start developing apps on top of the HOPR network by learning how to send and read messages from one node to another.

## Requirements​

### 1. Previous guides​

Before getting started, we suggest you get familiar with the following concepts:

### 2. HOPR Cluster & exported variables​

Make sure you have a HOPR cluster1 available for you to connect. Also, make sure to have the equivalent of at least 2 nodes endpoints (both HTTP and WS). Here are the default values for each of these endpoints.

Default values for apiToken and nodes endpoints

### apiToken

^^LOCAL-testing-123^^

### HOPR_NODE_1_HTTP_URL

http://127.0.0.1:13301

### HOPR_NODE_1_WS_URL

http://127.0.0.1:19501

### HOPR_NODE_2_HTTP_URL

http://127.0.0.1:13302

### HOPR_NODE_2_WS_URL

http://127.0.0.1:19502

We'll assume your HOPR nodes had been run with "Instructions for setting a local HOPR Cluster". If you are looking to interact with your node via a terminal, we suggest you to copy/paste the following commands every time you open a new terminal.

export commands for terminal

### API Token

export apiToken=^^LOCAL-testing-123^^

### Node 1

export HOPR_NODE_1_HTTP_URL=http://127.0.0.1:13301 HOPR_NODE_1_WS_URL=ws://127.0.0.1:19501

### Node 2

export HOPR_NODE_2_HTTP_URL=http://127.0.0.1:13302 HOPR_NODE_2_WS_URL=ws://127.0.0.1:19502

### All in one line

export apiToken=^^LOCAL-testing-123^^ HOPR_NODE_1_HTTP_URL=http://127.0.0.1:13301 HOPR_NODE_1_WS_URL=ws://127.0.0.1:19501 HOPR_NODE_2_HTTP_URL=http://127.0.0.1:13302 HOPR_NODE_2_WS_URL=ws://127.0.0.1:19502

### 1. Connect to the WebSocket server of node 2​
Using websocat or any other WebSocket client, connect to your node 2 until you are able to receive and send messages to it.
Connecting to node 2 via websocat