QUIC instead of TCP: what is happening with internet protocols in 2025

• TCP — a reliable and slow protocol
• QUIC — a new transport star based on UDP
• Why website owners should care about QUIC
• How to switch to the QUIC internet protocol
• How to check for HTTP/3 on a website
• Old is also effective: why QUIC did not replace TCP

You use Google, YouTube, TikTok, Facebook every day, but you haven't noticed the changes with internet protocols that directly affect the speed and security of data transmission. The TCP and HTTP/2 protocols that millions of websites rely on are gradually giving way to new technologies — QUIC and HTTP/3. While users don't necessarily need to delve into technical details, website owners need this information to improve SEO and user experience. It can help attract and retain more traffic in the era of rapid artificial intelligence development and global Google updates.

TCP — a reliable and slow protocol

The history of TCP began in the 1960s. At that time, the Pentagon's ARPANET prototype needed a way to exchange data between computers, but the networks were simple, and data was lost due to noise in the lines or equipment failures. In 1974, scientists Vinton Cerf and Robert Kahn proposed an improved way of data transmission — the Transmission Control Protocol. By 1984, primitive protocols based on NCP were replaced with TCP/IP, making networks resilient to failures.

In the 1990s, TCP became the foundation of HTTP/1.0. It became even more important during the development of the Netscape web browser family and the eBay marketplace, and in the 2000s — YouTube and Facebook. In 2014, HTTP/2 was released, allowing multiple requests and responses to be sent simultaneously over a single connection, minimizing the risk of parsing errors and reducing data volume. And it uses TCP for data transmission.

However, since the advent of the Transmission Control Protocol, HTTP/1.0, and HTTP/2, the internet has changed dramatically. Now, a single webpage consists of dozens or hundreds of simultaneous requests. People often switch between Wi-Fi and mobile networks, and they need a fast and uninterrupted connection. The market is so saturated that users no longer want to wait even 5 seconds — they need instant content loading, or they simply go to competitors.

And this is where the significant drawbacks of TCP become apparent:

• Multi-step connection establishment. To transmit data, the Transmission Control Protocol requires several steps of signal exchange, which takes only seconds, but in today's world, that's too much.
• Complex verification system. TCP is indeed reliable, as it will stop transmission if there is a delay or loss of even one packet until it receives it again. This creates delays even when most data is already ready.
• Problems in complex conditions. It struggles when network switching occurs. In such cases, the connection drops, and the connection starts anew.

In 2025, Transmission Control Protocol will account for 62% of all traffic. It cannot be called unnecessary, as it provides reliability on banking websites, extremely high security when downloading files and sending emails. But for most standard websites, a new protocol with higher data transfer speeds is needed, especially considering Google's penalties for slow websites and the rapid development of artificial intelligence.

Also read: How to pull a website out of the traffic pit after Spam Update and AI Overviews

QUIC — a new transport star based on UDP

Before analyzing its key capabilities, it's worth taking a look at the unusual history of QUIC. It began development back in 2012 to speed up Chrome, as TCP was performing poorly on mobile networks at the time; for example, Gmail users often experienced lags. In 2016, QUIC was handed over to the international organization for technical standards and protocols IETF, but it only became a standard in 2021. The hypertext transfer protocol HTTP/3 (based on QUIC) was officially approved in June 2022.

We would like to highlight several important advantages of QUIC over TCP:

• Ultra-fast connection. The Transmission Control Protocol spends relatively much time confirming both parties' readiness to communicate, after which encryption setup occurs. QUIC minimizes time costs by combining transport connection and encryption, and for reconnections to the same server, it can skip these steps altogether. That is, when connecting, instead of 3 rounds with waiting times of 200–500 ms, it goes through 1 round in 50–100 ms, or the connection occurs instantly.
• Minimal delays. If during data transmission one part is delayed, QUIC does not block all others. This is especially important for loading web pages with many resources, such as CSS, JavaScript, and images, as it allows providing content to the user without delays.
• Security by default. TCP works with TLS protocol as follows: first, a connection is established, and then encryption is added. QUIC has built-in encryption to protect data and connection metadata, meaning each connection uses TLS 1.3 by default.
• Seamless changes. Imagine a situation: you are watching the long-awaited new season of "Stranger Things" on home Wi-Fi, and suddenly the power goes out, and your phone switches to mobile internet. With TCP, the connection will be broken, and the series will stop or restart. With QUIC, the stream will continue, as it uses a unique connection identifier (Connection ID) that remains even after your IP address changes.

The key advantage of QUIC — is the combination of fast UDP and reliable TCP. It adapts instantly to network conditions and improves user experience, which is why it is increasingly being used on modern websites.

Also read: How to adapt your website for mobile devices

Why website owners should care about QUIC

Thanks to the aforementioned advantages and Google's support, QUIC transitioned quite quickly from testing to implementation after standardization. According to W3Techs data, by November 2025, HTTP/3 is used on 36.2% of all websites worldwide, and among the largest global portals — up to 60%. Supporters of the new protocol include YouTube, TikTok, Instagram, Pinterest, LinkedIn, Facebook, Netflix, Amazon. It is supported by most browsers, including Chrome, Mozilla Firefox, Safari, Edge.

But what does HTTP/3 have to do with QUIC? HTTP is the hypertext transfer protocol that defines the rules for interaction between the browser and the server for data exchange. Two well-known versions of HTTP/1.1 and HTTP/2 depend on TCP. However, the modern version HTTP/3 relies on QUIC, which allows websites to load faster. And website owners do not need to configure QUIC themselves — they just need to enable HTTP/3 on their dedicated server or CDN.

For online business owners, hosting a website on hosting that supports HTTP/3 provides the following advantages:

• More conversions. Web resources on HTTP/3 load 10-20% faster than on HTTP/2, and much faster than websites on HTTP/1.1. This already allows reducing the bounce rate and increasing sales. 
• Higher rankings in search results. Page loading speed is one of the official ranking factors for Google, so Core Web Vitals directly affect SEO. Based on the previous point: if a web resource loads not in 3-5+ seconds, but in 1-2 seconds, its chances of ranking higher in search results are greater.
• Stability for reputation. Switching from Wi-Fi to mobile internet and vice versa occurs with a delay. And no matter how good your product or service is, constant freezes of the web resource will harm the brand's reputation. The HTTP/3 protocol based on QUIC allows restoring the connection when changing networks in less than 50 ms, meaning the user won't even notice it. 
• Improved security. HTTP/3 has built-in encryption and better protects your customers' data. Moreover, it works more reliably in complex conditions, as lost data packets do not block the loading of the entire page, which is important for modern websites with diverse content (text, images, video, audio).

The benefits of using HTTP/3 are confirmed by large global companies. For example, Cloudflare in its report stated that with HTTP/3 enabled, the connection establishment time at P95 (95th percentile) decreased by 116 ms. Google Cloud reported back in 2021 that HTTP/3 helped them reduce video rebuffering time on YouTube by 9% and improve bandwidth on mobile devices by 7%.

How to switch to the QUIC internet protocol

The first way — choose a hosting provider that supports HTTP/3. Information about the protocol used by the company can be easily found on the website. You can check if the protocol support is enabled in the control panel. Later, we will explain in more detail how to check for HTTP/3 on a website.

The second way — use a CDN. For example, let's see how to enable HTTP/3 on Cloudflare:

1. Go to the main page of Cloudflare.

2. Register.

3. Add your domain. After that, the system will scan your site and find the DNS records. You will only need to change the default NS records to those provided by Cloudflare once.

4. Finally, go to your site in the Cloudflare system → Speed → Settings → Protocol Optimization.

As you can see in the screenshot, HTTP/3 should be enabled by default. That is, you only need to register, add a domain name, and change the NS records, and Cloudflare will automatically start responding to clients via QUIC.

How to check for HTTP/3 on a website

To check the QUIC connection to the site, use the free HTTP/3 Check service. Go to the main page, paste the link to your web resource, and click Check.

The service will instantly display information about the presence of HTTP/3 and QUIC on the site.

You can scroll down the page and view details on other metrics. But the main thing will be displayed in green immediately after your site's address — this is quite sufficient.

Also read: Key metrics for website loading speed: TTFB, FCP, LCP, and others

Old is also effective: why QUIC did not replace TCP

High speed, minimal delays, encryption by default, and support from a giant like Google — QUIC seems to be the ideal successor to TCP. However, at the time of writing this article, it is used on only 36.2% of websites, even though it has existed since 2012 and became an IETF standard in 2021. Meanwhile, TCP with HTTP/2 is used on 62.5% of internet projects, and it is unlikely to completely give way to the modern alternative.

And this raises the question: why has there not been a mass transition yet? In fact, the situation is much more complex than it seems, and a complete protocol change carries global risks. So let's break down the key reasons why QUIC has not fully replaced TCP yet:

• Distrust of UDP. QUIC is based on UDP, which many corporate networks and hardware devices block. This means the system tries to establish a connection via HTTP/3, encounters problems, and falls back to HTTP/2. Many enterprises do not want to update their network policies, as TCP has long been proven, and QUIC, while surpassing it, operates on the basis of UDP, which is generally viewed negatively.
• Reluctance to change. Business owners want to improve their products, and the modern protocol can help them with that, but action is required. And here lies the problem, as large companies have dozens/hundreds of servers that need to be updated. This entails a large volume of work, financial costs, testing, and risks of failures, which is the well-known principle of "if it works, don't touch it."
• Too encrypted. At the beginning of the article, we considered encryption by default as an advantage of QUIC, and for users, it is indeed so. However, corporate traffic analysis systems, attack detection tools, and deep packet inspection technology (DPI protection) are used to transparency in networks and do not want to lose the control that is much simpler on TCP.

In short: The internet is a conservative ecosystem, where slow changes protect against disasters. QUIC offers important advantages such as faster connection establishment and better user experience for mobile device users, but several factors hinder the complete transition from TCP to QUIC. Immediate transition is hampered by old network devices, corporate infrastructure, security concerns, and this is entirely normal for such global matters.

At the same time, competition between artificial intelligence and website owners is increasing, and Google is becoming stricter with internet projects. One way to attract the target audience and potential customers is to quickly provide useful information. And here comes HTTP/3 on QUIC, which can speed up web resources. As international companies have already shown, it is a plus for large sites with a mobile audience, streaming services, social networks, media projects, and interactive platforms.

So for now, QUIC does not replace TCP. Moreover, they will continue to work alongside each other for a long time. And HTTP/3 will simply become increasingly popular, especially where it truly provides benefits in the form of extremely fast, smooth, and secure data transmission.

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