Is there a way to make a Basic Auth with the Webserver?

I want to make a basic http auth in my webserver. I am using the ESP8266 Wifi.

You mean like this? https://developer.mozilla.org/en-US/docs­/Web/HTTP/Authentication

Yes, it should be pretty easy. Looks like all you're really doing is reading and setting headers on the HTTP response

Ok thank you.

For people who are interested here is an example:

First you look if the client is already logged in.
If not you send a Header with Status 401 and WWW-Authenticate.

// The header you check is "Basic Username:Password".
if(req.headers.Authorization != "Basic YWRtaW46YWRtaW4=") {
//Between the "" you can write a message that should than be displayed.
        res.writeHead(401, { 'WWW-Authenticate': 'Basic realm=""' });
        res.end();
} else {
        //If logged in
}

Edit:

Here is a little function.

function basicAuth(req, res, username, password, message, callback) {
    var credentials = btoa(username + ':' + password);
    if(req.headers.Authorization != "Basic " + credentials) {
        res.writeHead(401, {
           'WWW-Authenticate': 'Basic realm="' + message + '"'
        });
        res.write("401 Unauthorized");
        res.end();
    } else {
        callback();
    }
}

Thanks!