"Hello World" on WhatsApp

It's been 3 weeks of configuration. We went through SSH keys, Linux commands, memory Swap, Cloudflare Tunnels, and Docker files. All to arrive at this moment: seeing the message pop up on the phone.

Today, I wrap up this series by showing how I connected the brain (n8n) to the muscle (Evolution API).

1. The API Key Connection

For n8n to send messages, it needs authorization. In our configuration file, we defined a Global API Key. In n8n, we use the "HTTP Request" node. It's simple:

• Method: POST

• URL: https://api.mydomain.com/message/sendText

• Header: apikey: my-secret-password

2. The Fire Test

I created a simple flow: A Webhook that receives data -> A node that formats the text -> The request to the API. Clicking "Execute", the magic happened. The Oracle server (which cost me nothing) processed the data, talked to the WhatsApp container, and the notification buzzed in my pocket. Zero delay.

3. Was it worth it?

Let's look at the final numbers:

• Hardware Cost: $0.00 (Oracle Always Free).

• License Cost: $0.00 (Open Source).

• Domain Cost: ~$10.00/year (The only thing I paid for).

• Estimated Savings: $40.00 to $60.00 per month compared to SaaS or paid VPS solutions.

But the biggest gain wasn't financial. It was knowledge. I now have total control over my data, my security, and my infrastructure.

Thanks to everyone who followed this saga! Much more to come in 2026. Merry Christmas!