How we test VPNs in 2024

Virtual private networks (VPNs) are services that you can use to hide your online activity and obscure your digital footprint to prevent advertisers — and others — from tracking you. VPNs are also useful in bypassing firewalls, accessing content restricted to specific locations, and masking what websites you visit, and when. 

VPNs have become so popular that the digital marketplace is full of them. All VPN providers are competing for your attention and money (as the majority of VPNs are offered on a subscription basis), and it can be difficult to cut through the noise and find good, reputable VPN services suitable for your needs. 

This is where ZDNET comes in. Our experts provide hands-on reviews of the top VPNs on the market today, backed by extensive testing and research. This is how we test VPN software to make the right recommendations for you based on your needs.

How ZDNET tests VPNs in 2024

Nowadays, VPNs offer such an extensive list of features that choosing the right VPN can be a daunting and confusing experience. 

As the majority of reputable VPN services must be paid for, it is essential that you are able to either test out or pick the right VPN from the start. This becomes critical if you need extensive security, if you live somewhere known for censorship, or if you are in a country that frowns upon VPN usage — or bans it entirely outside of state-controlled solutions.

This is why ZDNET has developed a comprehensive testing structure that accounts for all of the major features VPN users want today: speed, stability, security, server availability, and flexible plans. We also want to see clear and transparent privacy policies, external security audits, warrant canaries, and a dedication to resolving security issues and vulnerabilities as they are reported.

We also consider a VPN’s other selling points, such as whether additional services are on the table — including cloud storage, password managers, and data breach scanners — and just how well these VPNs perform in typical home environments. 

A thorough ZDNET review of a VPN takes time, and includes multiple tests to ensure reliability, strong connectivity, and reasonable speeds. This independent process is necessary if we are going to give you authentic and genuine assessments of a VPN’s strengths, weaknesses, and how they perform over an extended period of time so that you can make an informed decision before taking the plunge. 

ZDNET VPN experts include David Gerwirtz, an expert in DIY IT and hardware, a US policy advisor, and a computer scientist. Together with Charlie Osborne, a cybersecurity journalist, and other ZDNET authors, we combine decades of experience using, testing, researching, and reviewing VPN software. 

We have run hundreds of speed tests on numerous VPNs throughout the years — including over a dozen VPNs more recently — and we have also conducted in-depth research on each VPN, including soliciting customer feedback and speaking to other experts. 

If a VPN is going to meet our standards as a top recommendation, it must perform well in numerous criteria. See below for the most significant criteria we test for, and how. 

How we test VPN speeds

Being able to recommend VPNs requires an extensive knowledge of a VPN’s performance during speed tests. 

In most cases, using a VPN will slow down your connection — there’s no avoiding it. As your traffic will be sent through encrypted tunnels and servers, VPNs become a middleman between your home connection and your desired location, protecting your data but also creating another stop on the journey. 

However, the best VPNs will not slow you down drastically in most circumstances. 

Speed is important. We like to reach our web destinations as quickly as possible. When you are looking for a new VPN, you will want to have an idea of how much the VPN might slow you down while browsing the web, streaming, or gaming. 

With this in mind, ZDNET attempts to replicate the typical conditions of a VPN user. We first measure our baseline upload and download speeds without a VPN and then we conduct further tests with the VPN enabled to ascertain how much speed is lost, if any. 

We also have the assistance of the CNET and ZDNET Lab, a dedicated team of data and product testing experts based in Louisville, Kentucky, who conduct further speed tests on our behalf. 

ZDNET uses Ookla’s Speedtest service, which is available online, to measure baseline and VPN speeds. This is an excellent and free test if you would also like to know if you are reaching the speeds your internet service provider has promised or if there are any connectivity problems reported in your area. 

As speed testing is not an exact science, speed results vary month to month, and they should only be taken as a rough guide rather than the specific results you should also expect. 

When we conduct our speed tests, we route traffic through a VPN’s server network in various locations. For example, we may test a VPN connection originating in the UK or US through servers located in European countries — or we may go as far as Australia. We may report on the specific upload and download numbers of our tests, or alternatively, we will provide a speed loss percentage. 

If we detect any anomalies or unusual results from our speed tests, we will note them in our reviews. For example, sometimes, a server may be particularly slow, and using it does not represent what the average user can usually expect from a VPN connecting in that country. In this case, we may switch servers — for example, moving from a Washington-based server to a server in New York — and we will note the change.

Some VPNs reduce your speed by a substantial amount, perhaps even as much as 50%. When assessing VPNs, we want to see an average speed loss of under 20%, although we do grant some leeway when servers are located over vast distances (such as from the UK to Australia). 

Below, you will see how we display the results in easy-to-understand graphs. 

How we assess VPN features

While conducting our assessments of VPNS, we consider the following features: 

Platform support

What systems and devices can you run the VPN on? Our recommended vendors must provide easy-to-use and intuitive desktop software and mobile apps. At a minimum, we want to see compatibility with Windows and Mac, and preferably Android and iOS. VPNs that also offer compatibility with routers, smart TVs, Chrome, Firefox, and Linux are preferred. 

Geoblocking and streaming

We know that VPNs can be key to accessing local content and services while you’re away from home. We test VPNs to see if they perform well in circumventing geographical locks. Furthermore, we try out streaming services, including Amazon Prime, Netflix, Disney+, and more to see if VPNs can access these libraries and do not noticeably slow down your connection or cause lagging while streaming. 

Countries and servers

Servers are important aspects of VPNs as they allow users to appear to be in different countries or locations, such as the US, Germany, or Singapore. The more server availability, the better — especially as this also helps share the load of user traffic, and you can switch between servers if you are connected to one that is too slow for your needs. We consider how many servers are on offer, and we want to see at least 40 to 50 locations, although we keep in mind that servers in some countries — such as Russia or China — are very rare considering their ruling authorities’ stance on VPN usage. 

ZDNET will also test a VPN’s “quick” or “smart” server connection features, which automatically select a server on a user’s behalf that will give them the best performance. 

Simultaneous connections

When you own multiple devices — such as a tablet, laptop, and smartphone — and use them for different tasks, you want to keep your data and connections secure on each machine. Enabling a VPN on more than one device at the same time means you are using simultaneous connections. 

It’s always best to have the option for simultaneous connections in a VPN to ensure your privacy isn’t accidentally compromised by switching between devices. 

ZDNET considers the number of simultaneous device connections available to subscribers within our evaluations. While some VPN providers only offer one or two, we prefer to see a minimum of six to eight simultaneous connections when you are paying for an ongoing plan.

Kill switches

One of the main features we insist upon when we recommend a VPN is the existence of a kill switch. Sometimes, our internet connectivity can unexpectedly drop, and this will also cause your VPN connection to fail. Your phone or computer is likely to immediately try to automatically reconnect to your internet service, and this will happen independently of any VPN you are running. 

All of a sudden, your data is unprotected, unless a kill switch is active. Kill switches detect when a connection fails and immediately shut down or pause network access, ensuring you are not sending out data or requests without the protection of an encrypted VPN tunnel. That’s not to say a kill switch is a perfect solution, but we cannot recommend VPNs that don’t provide their users with this feature.  

Extras

While the above features are the most important criteria we consider during VPN evaluations, we also research and may test additional features including password managers, cloud storage, antivirus software, browser extensions, and more. 

How we assess VPN security

A VPN is meant to be a tool to improve your security and privacy. 

There’s no point in using a VPN unless the vendor’s security protocols and encryption levels are up to scratch. We look for end-to-end encryption and the use of strong protocols including AES-256. 

It is also important that Domain Name System (DNS) leaks do not occur. DNS leaks can reduce the level of anonymity your VPN provides when operating systems use default DNS servers rather than a VPN’s servers, leading to information leaks. We use tools including DNSLeakTest.com.

The privacy policies of a VPN are very important. We investigate VPN privacy policies, paying particular attention to what information is collected about users, whether data is logged and if so, what categories of information, and whether or not any datasets are shared with third parties.

Furthermore, we make note of any external, independent security audits that have taken place — and how often they are repeated. As countries have different policies regarding data protection, we will take note of VPN providers that may be located in dubious areas, just as we will investigate whether or not VPN providers operate warrant canaries.

The best VPNs will also be transparent regarding bug fixes and will frequently issue patch updates to resolve vulnerabilities. ZDNET also likes to see advanced security features on offer, such as split tunneling, Tor over VPN, multihop connections, malware and antivirus solutions, phishing blockers, kill switches, and compromised credential alert systems. 

Generally, we will not recommend any VPN that does not have a clear privacy policy in place or that offers free services in exchange for your data. 

How we assess VPN value

The quality of a VPN must be assessed by combining the factors that are the most important to end users. 

Speed, security, stable connections, simultaneous connections, streaming service access, and any additional value-adding features, together with pricing, all influence ZDNET’s overall opinion of VPNs today. 

No VPN is perfect or a silver bullet for security. However, they add an important layer of security that can help protect your digital identity and reduce the risk of your online activities being tracked or monitored. 

Regarding pricing, we like to see flexible service options that range from a month to several years. A common phenomenon in the VPN space is the use of time-sensitive promotional deals and costs, and we understand that, sometimes, these deals aren’t all they are cracked up to be.

If a “sale” price is consistent — such as ExpressVPN’s “deal” on 12-month plans — we consider this to be the baseline price and we will note it as such. However, on occasions such as Black Friday and Thanksgiving, genuine promotions are possible. VPN vendors are also constantly changing their prices in response to rival organizations changing theirs. As a general rule, you will typically find the best deals for one-year and two-year plans, whereas month-to-month options are often expensive.  

It is important that VPN providers offer their users a money-back guarantee, which is typically 30 days. However, the longer, the better, as this gives users the chance to test out VPN software fully. We won’t recommend any VPN without a reasonable money-back guarantee. 

Frequently Asked Questions