SWG vs firewall: What's the difference?

representational image of a cloud firewall
(Image credit: Pixabay)

As the threat of online malware grows, many individuals and businesses are looking to take more steps to secure their networks. Secure web gateways (SWGs) and firewalls are two of the most commonly used security tools to protect yourself and other network users online.

An SWG and a firewall have overlapping but distinct purposes for protecting your network. In this guide, we’ll take a closer look at the differences between an SWG like Perimeter 81, and firewalls, and explain how you can combine them for maximum online security.

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Perimeter 81 is one of TechRadar's choices for the best SWG providers

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What is an SWG?

An SWG is a piece of software or hardware that analyzes data traffic between a computer or network and the internet. SWGs operate at a relatively high level, usually turning access to an entire website or online application on or off.

One of the ways in which an SWG can be used is to whitelist or blacklist specific URLs, thus enabling or preventing access to these websites. An SWG can also enforce network security policies by preventing a user from connecting to any unencrypted website or sending any unencrypted data.

SWGs can also be used in more specific ways. An SWG can automatically inspect outgoing data for social security numbers, medical information, or other sensitive information and prevent that data from being transmitted. It can even restrict the size of data packets that can be transmitted to or from a website, preventing malicious websites from siphoning off data from a network.

What is a firewall?

Like an SWG, a firewall sits at the boundary between a network and the internet at large. However, firewalls serve a different purpose from SWGs. They inspect individual data packets that are sent from a website to a network or from your network to a website. The code contained in each data packet is compared against a database of known malware to identify potentially malicious activity.

A lot of a firewall’s effectiveness depends on its known malware database and the quality of its code-matching tools. Many of the best firewall services incorporate artificial intelligence so they can also catch new malware that hasn’t been seen before, but shares similarities to known malware.

If a firewall does identify potentially malicious code, it will prevent that data packet from being passed on to your network. However, it won’t necessarily shut down all traffic from the infected website. This can be a benefit in some cases, but it can also mean that your network remains exposed to threats if you don’t have monitoring features or additional network controls in place.

SWG vs firewall: Key differences

An SWG and a firewall both protect your network from malicious websites. However, they go about doing so in distinct ways and have different capabilities.

An SWG provides customizable control over application-level data transfer between your network and a website. Data transfer can be turned completely on or off, such as by blacklisting sites or restricting all unencrypted data. Data transfer can also be limited or regulated based on criteria such as the site being visited, the network user accessing the site, or even the time of day.

A firewall identifies malicious code at the level of individual data packets. Firewalls are only modestly customizable since they depend heavily on databases of known malware. Any data packet that contains malicious code is automatically rejected from a network, but other data packets may continue to be transferred through the firewall. It’s important to keep a firewall up to date, or else new types of malware that aren’t found in an outdated database may slip through.

Another important distinction between SWGs and firewalls lies in how they handle outgoing traffic, such as data being transferred from your network to an external website or application.

SWGs monitor outgoing traffic and can be used to prevent sensitive data from being stolen by restricting the flow of any type of data you choose. Firewalls can also monitor outgoing traffic, but they’re primarily looking for data packets that contain malicious code. So, the outbound traffic features of a firewall limit the ability of malware to communicate with a command server after your network has been infected.

Using an SWG and firewall together

You can use an SWG and a firewall together to create a highly effective defense against online threats. A new type of network security framework, known as Secure Access Service Edge (SASE), is built using a combination of SWGs, firewalls, and network monitoring tools.

By using both an SWG and a firewall in combination, you gain the ability to filter traffic at the level of individual data packets (firewall) and whole web applications (SWG). The net result is that you can lock out malware, reduce the likelihood of human error causing a security breach, and limit the ability and damage of malicious code if it does get into your network. 

In fact, many of the best SWG solutions now incorporate the malware-blocking features of firewalls and many top firewalls are offering some of the application-level controls of SWGs. 

As the cybersecurity field continues to evolve, it’s likely we’ll start to see platforms that offer combined SWG and firewall defenses.


A secure web gateway, or SWG, enables you to control the flow of data between your network and the internet at the application level. A firewall works by filtering data packets to identify malicious code and prevent it from reaching your network.

Used together, an SWG and firewall can provide overlapping security tools that offer ransomware protection and defend against some of the biggest cybersecurity risks your business faces.

Michael Graw

Michael Graw is a freelance journalist and photographer based in Bellingham, Washington. His interests span a wide range from business technology to finance to creative media, with a focus on new technology and emerging trends. Michael's work has been published in TechRadar, Tom's Guide, Business Insider, Fast Company, Salon, and Harvard Business Review.