To use environment variables in your Netlify Functions, access the process.env variable:

process.env.YOUR_VARIABLE

You can use object destructuring at the beginning of your JS file, to make the code nicer:

const { YOUR_VARIABLE } = process.env;

so you can just use YOUR_VARIABLE in the rest of the program.

You set the variables through the Netlify administration interface (you can also add them in your repo, but I’d recommend using the Netlify UI so you have no secrets in your Git repository).

Note: this does not work on Netlify Edge Functions, just on Netlify “regular” Functions that run on AWS Lambda.

For Netlify Edge Functions, you need to use Deno.env.get(), like this:

Deno.env.get('YOUR_VARIABLE')

Example:

export default () => new Response(Deno.env.get('YOUR_VARIABLE'))