soapbox/docs/development/how-it-works.md

How it works

Soapbox is a single-page application (SPA) that runs entirely in the browser with JavaScript.

It has a single HTML file, index.html, responsible only for loading the required JavaScript and CSS. It interacts with the backend through XMLHttpRequest (XHR).

Here is a simplified example with Nginx:

location /api {
  proxy_pass http://backend;
}

location / {
  root /opt/soapbox;
  try_files $uri index.html;
}

(See mastodon.conf for a full example.)

Soapbox incorporates much of the Mastodon API, Pleroma API, and more. It detects features supported by the backend to provide the right experience for the backend.