How can I start a process from an external application (app)?

Hello, I’m trying to start a Camunda process with a HTTP Post Request, here is the code that I’m using:

import fetch from "node-fetch";

fetch("http://localhost:8080/engine-rest/", {
  method: "POST",
  body: JSON.stringify({
    userId: 1,
    title: "Fix my bugs",
    completed: false
  }),
  headers: {
    "Content-type": "application/json; charset=UTF-8"
  }
})
  .then((response) => response.json())
  .then((json) => console.log(json));

However I get this error:

The process that I’m trying to run/start is called ‘Prueba’. This process is already deployed, but I’m guessing my code needs this information in the arguments of fetch, nonetheless, it is not clear to me how the correct route should be:

http://localhost:8080/engine-rest/
http://localhost:8080/engine-rest/engine
http://localhost:8080/engine-rest//engine/Prueba

Note: I’ve already tried these 3 possibilites but I get the same mistake.

Here is Camunda diagram.
Prueba.bpmn (5.1 KB)

I’ve found that the URL is ‘http://localhost:8080/engine-rest/process-definition/key//start’

You have to change the with the process you have deployed.