What is HTTP/3? Pros and Cons, Features & Capabilities

Today, the internet is a vital part of our daily lives. We read the news, stream videos, and chat with friends online. But as the amount of data we exchange grows, so does the load on global networks.

HTTP (HyperText Transfer Protocol) has handled this traffic since 1991, evolving over the years. And now, the latest and most advanced version is here — HTTP version 3.

Using HTTP/3 helps web pages load faster, which is especially valuable when working with high-traffic systems such as proxies for web scraping or managing large inventories with eCommerce proxies. There are even rumors that HTTP/3 helps reduce account blocks when working with multiple profiles — though this is not officially confirmed.

So what is HTTP/3, how does it differ from previous versions, and what are the pros and cons?

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What is HTTP/3?

So, what is http3 exactly? It is the third major version of the HyperText Transfer Protocol. Unlike previous versions, it uses QUIC — a modern transport protocol built on UDP. This shift allows for faster, more secure, and more reliable web connections.

For example, when you're browsing the web or watching a video, HTTP/3 ensures quicker load times and smoother performance, even with packet loss. Major browsers and about 30% of websites already use HTTP version 3 in production.

If you’re interested in the differences, here is a brief comparison of http3 vs http2: HTTP/3 uses QUIC over UDP, providing faster connection setups and better performance on unreliable networks compared to HTTP/2’s TCP-based transport.

How Does HTTP/3 Work?

At its core, HTTP/3 replaces the traditional TCP transport with QUIC, a protocol built on UDP.
This shift means:

• Faster handshakes — QUIC combines transport and encryption setup in one step, reducing latency.

• Multiplexed streams — data flows independently, so packet loss in one stream doesn’t block others.

• Built-in security — QUIC integrates TLS 1.3 by default, ensuring every connection is encrypted.

By leveraging UDP and managing reliability at a higher level, HTTP/3 achieves quicker, more stable, and more secure connections compared to TCP-based versions.

To understand how to use http/3 effectively, it’s important to know its core principles and benefits.

Key Features of HTTP/3

Protocol based on QUIC

Previous versions used transport layer protocols UDP (User Datagram Protocol) and TCP (Transmission Control Protocol), each with its own advantages and disadvantages.

TCP ensures reliable data delivery and guarantees the correct order of files without loss or duplication, but it requires establishing a connection or confirming data delivery, which affects the protocol's speed. Meanwhile, the transport protocol UDP has a higher data transmission speed but is less reliable than TCP since packet loss is possible.

To address these issues, Google developed the transport protocol QUIC (Quick UDP Internet Connections), the main http/3 feature, which takes the best from both worlds, while eliminating their drawbacks:

• Fast Connection. QUIC allows establishing communication between the client and server almost instantly, which is crucial for applications requiring high speed.
• Multiplexing. Enables simultaneous transmission of multiple data streams within a single connection, contributing to faster loading of web pages in browsers.
• Encryption. Applied by default, allowing secure data transmission even in insecure networks.
• Congestion Control. Includes flow control algorithms that help manage data transmission speed, ensuring stable file transmission and preventing network congestion.
• Mobile Devices. Consume fewer resources for data transmission and enhance application performance through rapid connection establishment and efficient resource management.
• Open Source. QUIC is open-source, and any developer can utilize it.
• Extensions. Open for additional features later on.

Multiplexing

In previous versions of HTTP, the loss of a single packet could lead to head-of-line blocking, resulting in the blocking of the entire remaining stream. However, HTTP/3 does not limit the number of concurrently open streams, and the bloking of one does not affect others. The main benefits of multiplexing are:

• Improved Performance. Significantly reduces webpage loading times and decreases latency during data transmission.
• Resource Efficiency. Reduces the use of network resources for establishing and maintaining connections.
• Reliability. Parallel transmission of data streams makes web applications more resilient to failures and overloads.

Security

HTTP/3 always applies TLS 1.3 (Transport Layer Security version 1.3) - the latest version of the encryption and data protection protocol at the transport layer. This involves using a new mode of initial connection (TLS Handshake) with the Diffie-Hellman (DH) protocol, which provides additional security and protection against attacks. All sessions established using TLS 1.3 automatically provide Perfect Forward Secrecy (PFS), which helps protect previously encrypted traffic even if the key is compromised. The use of the Diffie-Hellman protocol reduces the set of ciphers, reducing the amount of transmitted data and the overhead of establishing a secure connection.

Packet Loss Recovery

This mechanism ensures that lost packets are retransmitted within each stream without delaying other streams. Unlike previous versions, packet loss does not block the transmission of other streams, improving connection speed and stability, especially on unreliable networks.

Fast Session Resumption

QUIC’s fast session resumption (0-RTT) lets clients reconnect to a server almost instantly by reusing encryption keys from a previous session. This reduces the time needed to establish a secure connection, cutting latency for repeat visits and improving load speeds for returning users.

Advantages of HTTP/3

HTTP/3 provides many practical http 3 advantages:

• Faster website interaction. HTTP/3’s streamlined connection setup and efficient data handling translate into noticeably quicker page loads and smoother user interaction compared to older protocols.

• Better content delivery responsiveness. The protocol’s design reduces delays in content distribution networks, allowing websites and services to deliver content more promptly to users worldwide.

• Superior performance on mobile networks. HTTP/3 adapts seamlessly to changing network conditions such as switching between Wi-Fi and cellular, minimizing interruptions and maintaining smooth connectivity on mobile devices.

• Greater reliability under poor network conditions. Thanks to improved packet loss handling, users experience fewer connection drops and less buffering even on unstable or congested networks.

These http/3 benefits make the protocol a powerful choice for modern web browsing and applications.

Disadvantages of HTTP/3

While HTTP/3 brings significant improvements compared to previous versions, it also has its potential limitations and drawbacks:

• Migration. Transitioning to HTTP/3 may require network and server infrastructure updates, which can be a complex and costly process.
• UDP Packet Blocking. UDP is considered less secure, which is the main reason why many firewalls block it, which leads to difficulties in configuring firewalls to prevent blocking of HTTP/3 requests.
• Limited Support. Not all servers and clients support HTTP/3, which may restrict the protocol's availability. Compatibility issues with existing security measures and debugging tools may arise.
• Increased Complexity. HTTP/3 is a more advanced protocol compared to previous versions, which can complicate its implementation and debugging. Additionally, there is much less available information about it compared to HTTP/2.

Consider iProxy Your Trusted Partner

With iProxy, you can run automated tools, manage ads, or work with large datasets using mobile proxies that support HTTP version 3 via oVPN.

We help clients optimize scraping setups, automate eCommerce operations, and ensure reliable performance even in high-demand environments. Whether you're handling traffic or need consistent mobile IPs, our solutions work effectively under any condition.

Explore our guide on what is a mbit/s and other resources to better understand network performance and bandwidth when scaling your business.

Take action and switch to iProxy today — the trusted mobile proxy provider for a high-performance internet with HTTP/3 support.