How to Enable HTTP/2 on Your Web Server

What the check tests

SiteCurl opens a TLS connection to your server and checks whether it advertises HTTP/2 support through ALPN (Application-Layer Protocol Negotiation). If the server responds with h2, it supports HTTP/2. If it responds with http/1.1, it does not.

HTTP/2 requires HTTPS. If your site uses plain HTTP, this check is skipped because the protocol is only available over encrypted connections.

Why it matters

HTTP/1.1 opens a separate connection for every file the browser needs: HTML, CSS, JavaScript, images, fonts. Each connection has overhead from TCP handshakes and TLS negotiation. On a page that loads 40 resources, that overhead adds up.

HTTP/2 multiplexes all requests over a single connection. The browser can request every file at once without waiting for previous downloads to finish. The result is faster page loads with less server overhead.

Most modern browsers have supported HTTP/2 for years. The bottleneck is usually the server setup, not the browser.

How to fix it

Nginx

Nginx 1.9.5+ supports HTTP/2. Add http2 to your listen directive:

server {
    listen 443 ssl http2;
    server_name example.com;
    # ... SSL config
}

Reload the config: sudo nginx -s reload.

Apache

Enable the http2 module and add the protocol directive:

# Enable the module
LoadModule http2_module modules/mod_http2.so

# Add to your virtual host
Protocols h2 http/1.1

Restart Apache: sudo systemctl restart apache2.

Managed hosting

Most managed platforms (Cloudflare, Netlify, Vercel, Render, AWS CloudFront) enable HTTP/2 by default. If you are behind Cloudflare, HTTP/2 is on automatically. For other CDNs, check the settings panel for an HTTP/2 toggle.

How to verify the fix

Run a SiteCurl scan and check the speed section for the HTTP/2 finding. You can also verify from the command line:

curl -sI --http2 https://example.com | head -1
# Should show: HTTP/2 200

Related checks

HTTP/2 pairs well with other speed optimizations. If your server is fast but pages still load slowly, check Core Web Vitals and render-blocking resources.

Start a free trial to check HTTP/2 support across your site.