HTTP/2 in Practice: Adoption, Configuration, and Measurable Results

HTTP/2 is standardised and browser support is nearly universal. A practical guide to deploying HTTP/2, measuring performance, and solving common issues.

State of Adoption in 2016¶

HTTP/2 browser support has reached critical mass — Chrome, Firefox, Edge, Safari, and Opera cover over 80% of users. On the server side, nginx 1.9.5+, Apache 2.4.17+, and all major CDNs (CloudFlare, Fastly, Akamai) support HTTP/2.

Yet most websites still run on HTTP/1.1. The main reason? HTTPS as a prerequisite — but with Let’s Encrypt, this is no longer an obstacle.

Configuring nginx for HTTP/2¶

Enabling HTTP/2 in nginx is a one-line change:

server {
    listen 443 ssl http2;
    server_name example.com;

    ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem;

    # Modern SSL configuration
    ssl_protocols TLSv1.2;
    ssl_ciphers HIGH:!aNULL:!MD5;
    ssl_prefer_server_ciphers on;

    # HSTS
    add_header Strict-Transport-Security "max-age=31536000" always;
}

One word — http2 — in the listen directive. Nginx automatically falls back to HTTP/1.1 for older clients.

Measurable Results¶

Our measurements on real projects show:

• E-commerce page (50+ resources) — 30% improvement in load time
• SPA with API calls — 15-20% improvement thanks to multiplexing of API requests
• Content site with many images — 25% improvement, elimination of domain sharding

The biggest benefit is on pages with many small resources — exactly where HTTP/1.1 suffers from head-of-line blocking.

Server Push and Optimisation¶

HTTP/2 Server Push proactively sends resources:

location / {
    http2_push /css/app.css;
    http2_push /js/app.js;
}

Beware of over-pushing — unnecessary pushes waste bandwidth. Measure what helps:

• Push critical CSS and JS
• Do not push images (too large)
• Respect the cache — do not push what the client already has cached
• Consider 103 Early Hints as an alternative

Conclusion: Migration is Easy, Benefits are Real¶

HTTP/2 migration is low-hanging fruit — minimal effort, measurable performance improvement. If your website runs on HTTPS (and it should), add HTTP/2 today. Measure results with WebPageTest or Lighthouse.