js example of adding app identification headers to openlibrary.org API calls

ol_api_header_example.js

const url = "https://openlibrary.org/search.json?q=test";
const headers = new Headers({
    "User-Agent": "MyAppName/1.0 (myemail@example.com)"
});
const options = {
    method: 'GET',
    headers: headers
};
fetch(url, options)
    .then(response => response.json())
    .then(data => console.log(data))
    .catch(error => console.error('Error:', error));

It's a network request so you should be able to adapt this to any language.