What is Cloudflare, and why did half the internet go down on Nov 18?

Following the outage, the company acknowledged a service issue that affected multiple customers, triggering error messages and disrupting connections to application programming interfaces (APIs). All of this raises the question: what is Cloudflare, and how big is it?

What is Cloudflare?

Cloudflare Inc. is a US-based company that delivers content delivery network (CDN) services, cybersecurity solutions, and most importantly prevention of distributed denial of service (DDoS) attacks, etc. It is among the most influential companies on the internet, even though it remains largely obscure to everyday users.

The company offers a cloud-based service that acts as a security shield, or simply a traffic manager, and even a performance booster for millions of websites across the globe.

“Cloudflare is built on an intelligent, secure, high-speed global network. We help businesses regain control of their technology and security environments by reducing complexity and improving visibility across their on-premises, public cloud, SaaS and public Internet domains. For individuals, we make the Internet safer, faster and more private,” reads the company’s official website.

Cloudflare was founded in 2009 by Matthew Prince, Lee Holloway, and Michelle Zatlyn. The company is headquartered in San Francisco, California and some of its notable products include 1.1.1.1 DNS resolver, the WARP VPN client, the Cloudflare Workers server-less platform and its SASE (Secure Access Service Edge) suite.

As of November 2025, the company claims to have a market cap of $69.14 billion, and employs over 4,250 worldwide. Reportedly, Cloudflare’s services are used by roughly 19.3 per cent of all websites on the Internet as of January 2025.

What does Cloudflare do?

Cloudflare can be termed as the internet’s backstage crew. While a user may not see it while accessing a website, it is working behind the scenes continuously to ensure that the page loads quickly and stays protected from attacks. To further simplify, Cloudflare actually takes care of three things – security, performance, and traffic management.

When it comes to security, it essentially protects websites from cyberattacks, particularly DDoS attacks that aim to overwhelm sites with fake traffic. It filters harmful requests much before they can reach a website’s servers. On the performance side, Cloudflare accelerates content delivery by storing cached versions of webpages in data centres installed worldwide. In simple words, when a user clicks on something, the page loads from the nearest Cloudflare location instead of a distant server.

Another key area is reliability and traffic management. Cloudflare routes internet traffic efficiently so websites don’t crash in moments of sudden spikes. It also helps maintain the uptime by managing the overloads, rerouting traffic when servers fail.

The company also sells cybersecurity solutions to companies to build websites and applications to safeguard them against threats. It operates a network that ensures safe transfer of data instantly and securely. The company distributes internet traffic throughout its network to optimise performance.

Above all this, Cloudflare operates on an unimaginable scale. This also means that any interruptions would ripple outward in a way few other companies can match. Simply put, when Cloudflare stumbles, millions of websites feel the tremors.

Why did the latest outage hit so hard?

Tuesday’s outage showed just how many services are dependent on Cloudflare each day. From social media to productivity tools, to AI platforms, Cloudflare’s infrastructure supports a significant section of the global internet. And, when Cloudflare’s networks had issues, the services built atop went down.

The technical messages that appeared on error pages was the indication. These messages served as digital fingerprint pointing at Cloudflare’s systems rather than servers of individual companies. When Cloudflare identified and fixed the issue, websites across the internet came back to life.

While most users may not think about Cloudflare, yet its role is enormous. It secures websites, enhances loading speeds, blocks malicious attacks by the second. It is a platform that houses companies of all sizes, from small blogs to giant e-commerce companies.