plausible.io is my favourite Analytics service out there. It's open-source and you have the ability to self-host it.

CORS my dear friend

I had the idea to show the realtime visitors on this site, but encountered my favourite HTTP obstacle: CORS

With a small HTTP proxy you can circumvent this limitation!

plausible-current-visitors-proxy is a small module that spins up an HTTP server that simply proxies your request to Plausible.io's API and returns the current visitors.

Something like 10 lines of code.

HTTP Proxy Server

Here is how you can use it.

Install it via npm i -g plausible-current-visitors-proxy.

Then you can run it on your own server with

DOMAIN=cri.dev plausible-current-visitors-proxy
> server listening at http://127.0.0.1:54151

curl http://127.0.0.1:54151
> 2

CloudFlare Workers

The very same can be achieved with a simple CloudFlare worker!

Here the source code for the worker:

addEventListener('fetch', event => {
  event.respondWith(handleRequest(event.request))
})

async function handleRequest(request) {
  const domain = 'cri.dev'
  const url = `https://plausible.io/api/stats/${domain}/current-visitors`
  const res = await fetch(url)
  const currentVisitors = await res.text()
  return new Response(currentVisitors, {
    status: 200,
    headers: {
      'Access-Control-Allow-Origin': '*',
      'content-type': 'text/plain'
    }
  })
}

You'll get your CloudFlare Worker URL, which will be needed.

Once configured, you can get the current visitors with a fetch request:

const response = await window.fetch('https://current-visitors.cri.dev/')
const currentVisitors = +await res.text()

JavaScript widget

The idea for the widget is simple:

You have a container in the DOM, in which you render the current visitors.

Periodically updating the current visitors.

Something like this

getCurrentVisitors().then(showCurrentVisitors)
setInterval(() => getCurrentVisitors().then(showCurrentVisitors), 10000)

function showCurrentVisitors (currentVisitors = 0) {
  const container = document.getElementById('current-visitors-container')
  if (!container) return console.info('no container to show current visitors found')
  container.innerHTML = `
  <a aria-hidden tabindex="-1" href="https://plausible.io/cri.dev" rel="nofollow noopener external" target="_blank">
    ${currentVisitors}&nbsp;<svg width="1em" height="1em" viewBox="0 0 16 16" class="bi bi-person" fill="currentColor" xmlns="http://www.w3.org/2000/svg"><path fill-rule="evenodd" d="M10 5a2 2 0 1 1-4 0 2 2 0 0 1 4 0zM8 8a3 3 0 1 0 0-6 3 3 0 0 0 0 6zm6 5c0 1-1 1-1 1H3s-1 0-1-1 1-4 6-4 6 3 6 4zm-1-.004c-.001-.246-.154-.986-.832-1.664C11.516 10.68 10.289 10 8 10c-2.29 0-3.516.68-4.168 1.332-.678.678-.83 1.418-.832 1.664h10z"/></svg>
  </a>
  `.trim()
}

function getCurrentVisitors () {
  return window.fetch('https://current-visitors.cri.dev/')
    .then((res) => res.text())
}

The style it accordingly to your preferences.

This is the CSS used to show it on this site:

#current-visitors-container {
  position: fixed;
  bottom: 0;
  right: 0;
  padding: 0.75em 1em;
  opacity: 0.3;
  font-size: 0.9em;
}

#current-visitors-container:hover {
  opacity: 1;
}