Static HTML
Use Static HTML for sites that only need HTML, CSS, browser JavaScript, images, and other client-side assets. It is the simplest option for portfolios, landing pages, documentation, and frontends that call external APIs.
Node.js
Use Node.js when your application runs a JavaScript server such as Express or another Node-based backend. Your project normally needs package.json and the entry file expected by the startup command.
Python
Use Python for Flask, FastAPI, Django-style applications, APIs, bots with a web frontend, or other Python services. Include the Python source and dependency list your project requires.
PHP
Use PHP for PHP applications and scripts that must execute on the server rather than being served as plain text.
Changing the runtime changes how the server starts and which container environment it uses. Pick the runtime that matches the application instead of trying to force a project into the wrong server type.