Guide to Setting the "Referrer-Policy" Header

Contents

What Does This Header Do?

The Referrer-Policy header controls how much information about the URL of the referring page is shared when navigating to another website. By limiting or anonymising referrer data, this header helps protect user privacy and prevent sensitive information leaks.

Steps to Set the Header

1. If You Use a Web Server (e.g., Apache, Nginx, etc.)

For Apache:

  1. Open your website's configuration file (or .htaccess file if you use one).
  2. Add the following line, replacing no-referrer with the policy that fits your needs: 
    Header set Referrer-Policy "no-referrer"
  3. Save the file and restart the Apache server to apply changes.

For Nginx:

  1. Open your website's configuration file (e.g., /etc/nginx/sites-available/your-site).
  2. Add the following line inside the server block, replacing no-referrer with the policy that fits your needs: 
    add_header Referrer-Policy "no-referrer";
  3. Save the file and restart Nginx to apply changes using: 
    sudo systemctl restart nginx

2. If You Use a Programming Language:

For PHP:

header("Referrer-Policy: no-referrer");

For Node.js:

Use a middleware like helmet to set the header automatically:

const helmet = require('helmet');
app.use(helmet.referrerPolicy({ policy: 'no-referrer' }));

Or set it manually:

app.use((req, res, next) => {
  res.setHeader('Referrer-Policy', 'no-referrer');
  next();
});

For Python (Flask):

from flask import Flask, Response

app = Flask(__name__)

@app.after_request
def set_headers(response):
    response.headers['Referrer-Policy'] = 'no-referrer'
    return response

3. Verify the Header

After setting the header, test your website to ensure it’s working:

  1. Open your website in a browser.
  2. Use the developer tools (right-click > Inspect > Network tab) to view the HTTP headers.
  3. Look for the Referrer-Policy header with the correct value.

Why It Matters

Setting this header helps protect user privacy by controlling the information shared in referrer URLs, reducing the risk of leaking sensitive data to third-party websites or attackers.