You can read environment variables directly in your web application via import.meta.env. If you’ve ever used process.env in Create React App or any Webpack application, this behaves exactly the same.

For your safety, Snowpack supports only environment variables which begin with SNOWPACK_PUBLIC_*. We do this because everything in your web application is sent to the browser, and we don’t want you to accidentally share sensitive keys/env variables with your public web application. Prefixing your frontend web env variables with SNOWPACK_PUBLIC_ is a good reminder that they will be shared with the world.

// `import.meta.env` - Read process.env variables in your web app
fetch(`${import.meta.env.SNOWPACK_PUBLIC_API_URL}/users`).then(...)

// Supports destructuring as well:
const {SNOWPACK_PUBLIC_API_URL} = import.meta.env;
fetch(`${SNOWPACK_PUBLIC_API_URL}/users`).then(...)

// Instead of `import.meta.env.NODE_ENV` use `import.meta.env.MODE`
if (import.meta.env.MODE === 'development') {
  // ...

import.meta.env.MODE and import.meta.env.NODE_ENV are also both set to the current process.env.NODE_ENV value, so that you can change app behavior based on dev vs. build. The env value is set to development during snowpack dev and production during snowpack build. Use this in your application instead of process.env.NODE_ENV.

You can also use environment variables in HTML files. All occurrences of %SNOWPACK_PUBLIC_*%, /, and production will be replaced at build time.

Remember: that these env variables are statically injected into your application for everyone at build time, and not runtime.