Varnish cache vs. LiteSpeed cache: Which is better for your web application?

Caching is a crucial aspect of optimizing web application performance. Caches store frequently accessed data locally, which reduces the need to fetch it from the server on every request, resulting in faster load times.

This guide compares two popular caching solutions: Varnish Cache and LiteSpeed Cache. It will explore their key features, benefits, and potential drawbacks to help you make an informed decision about the cache that’s best suited to your use case.

Overview of Varnish Cache

Varnish Cache is an HTTP reverse proxy known for its high-performance caching capabilities. It sits in front of a web server and stores copies of web pages or other content in memory. This allows it to serve them quickly to visitors without needing to go back to the server for each request.

Varnish is widely used to improve web performance, reduce server load, and increase the number of users a site can handle. It’s especially useful for content-heavy websites like news portals or e-commerce platforms, where faster loading times can enhance user experience.

Here are some notable features of Varnish:

• Edge Side Includes (ESI): Supports partial caching of pages to keep dynamic and static content separate.
• Load balancing: Offers load balancing capabilities out of the box.
• Advanced purging options: Allows precise control over clearing cache when content is updated.

How does it work?

Varnish intercepts and caches HTTP requests. It uses a powerful configuration language called VCL (Varnish Configuration Language), which allows developers to granularly define what content to cache, for how long, and under what conditions.

When a request comes in, Varnish checks if the requested content is available in its cache. If it's found, Varnish serves it directly to the user, bypassing the backend server. If not, Varnish fetches it from the server, caches it, and serves it to the user.

Overview of LiteSpeed Cache

LiteSpeed Cache is a server-level cache provided by LiteSpeed Web Server. It’s designed to speed up websites and web applications, specifically in environments running the LiteSpeed web server.

Like Varnish, LiteSpeed Cache is used to boost performance by storing pre-built versions of web pages and reducing load times. It’s favored for dynamic content-heavy websites, and it integrates well with several web applications.

Here are some notable features of LiteSpeed Cache:

• Image optimization: Includes built-in tools to optimize images and minify CSS/JS files.
• QUIC and HTTP/2 support: Has built-in support for modern web protocols to enhance performance further.
• Automatic purging: Clears cache intelligently when content changes, ensuring that the latest version of content is served every time.

How does it work?

Unlike Varnish, which is a standalone reverse proxy, LiteSpeed Cache is part of the LiteSpeed Web Server. It works at the server level, caching both static and dynamic content. However, there are also LiteSpeed Cache plugins available for different platforms, including WordPress, Magento, Joomla, and OpenCart. You also have the option to develop your own LiteSpeed Cache plugin.

Performance and scalability comparison

When it comes to performance and scalability, both caches have their strengths, but their architectural differences significantly impact how they handle web traffic and scale. Let’s explore further.

Varnish

Since Varnish is designed specifically as an HTTP accelerator, it can handle a massive number of simultaneous requests and serve cached content directly from memory. This results in incredibly fast response times for cached content. ESI in Varnish allows for partial page caching, which can improve performance on pages where some elements are dynamic and others are static.

Varnish is highly scalable, which is why it’s often used in large-scale content delivery networks (CDNs) and media-heavy websites. As a reverse proxy, Varnish can distribute requests across multiple backend servers, reducing the load on the server infrastructure. Additionally, its efficient memory usage helps Varnish maintain a low resource footprint while handling large volumes of traffic.

However, Varnish is not ideal for dynamic content out of the box — it’s primarily designed for static content. For highly dynamic sites, additional configurations or integration with other tools are required.

LiteSpeed

Since LiteSpeed Cache is integrated directly into the LiteSpeed Web Server, it can cache both static and dynamic content with ease. This server-level integration means that there’s no need to have a separate caching layer, which in turn reduces overhead and response time.

LiteSpeed also has several built-in optimizations, such as image compression, CSS/JS minification, and support for HTTP/2 and QUIC. These features collectively improve page load times and scalability, especially for content-heavy or e-commerce sites.

One advantage of LiteSpeed Cache is its ability to handle dynamic content better than Varnish, especially for WordPress and other CMS-driven sites. However, the fact that it is tied to the LiteSpeed Web Server may limit its scalability in non-LiteSpeed environments.

Compatibility and integrations

Next, we will evaluate Varnish and LiteSpeed caches in terms of compatibility and interoperability.

Varnish

Varnish Cache is highly flexible and compatible with almost any web server or application stack. It is platform-agnostic, meaning it can work with most web servers, including Apache, NGINX, and any other backend.

Since it operates as an HTTP reverse proxy, you can place it in front of any web server or application that communicates using HTTP. Varnish also works well with CDNs, making it a common choice for large-scale deployments where caching is needed across multiple servers.

Varnish is relatively easy to add to most environments due to its flexibility, but it may require more effort in terms of configuration. Developers will need to have a solid understanding of VCL to fine-tune caching rules for their specific use case. While it is not tied to any particular web server, its implementation can be more complex when compared to a built-in cache like LiteSpeed.

LiteSpeed

LiteSpeed Cache is tightly integrated with the LiteSpeed Web Server, meaning it works best in environments already using LiteSpeed. The built-in cache requires little configuration. However, this deep integration can also be seen as a limitation, as it doesn’t work with non-LiteSpeed environments like Apache or NGINX.

To use LiteSpeed Cache to its full potential, you must switch your web server to LiteSpeed, which may not be feasible for everyone. That said, if you have a CMS-based deployment, you can leverage LiteSpeed plugins to set up caching.

These plugins allow you to configure features like page caching, object caching, and automatic cache purging directly from the CMS dashboard without having to touch any configuration files. It’s also possible to develop your own custom LiteSpeed Cache plugin, but this would require deep knowledge of the cache’s internals.

Flexibility

Flexibility is a fundamental consideration when choosing a caching solution. This section will compare the configurability and extensibility of both caching platforms.

Varnish

Varnish Configuration Language (VCL) allows developers to define complex caching rules and behaviors. They can control different aspects of caching, such as caching methodology, request handling, timeouts, health probes, query string sorting, and more.

For example, you can create caching policies that vary depending on request headers, cookies, or user location. You can also implement advanced cache purging strategies and configure tag-based caching for efficient updates.

However, this flexibility comes at a cost. For users who are unfamiliar with VCL, the configuration process can be challenging, and changes can introduce complexity into the setup.

In terms of extensibility, Varnish scores high marks. Its modular design allows it to work alongside various third-party tools and plugins. While Varnish itself focuses on caching HTTP requests, it can be extended with modules to handle SSL termination, logging, monitoring, and more. In addition, since it’s open-source, developers can even extend its core functionality per the specific needs of the business.

LiteSpeed

Unlike Varnish, which relies on custom scripting, LiteSpeed Cache comes with out-of-the-box configurations for common use cases, which significantly reduces the need for manual tweaking. Its interface is accessible through the CMS dashboard or the LiteSpeed Web Server, allowing users to adjust cache settings without needing to write custom code or configuration scripts.

While LiteSpeed Cache offers enough customization for most users, such as excluding certain pages from caching or setting cache expiration times, it doesn’t have the same level of granular control that Varnish provides. That said, for most small- to medium-sized websites, the built-in configurations are sufficient, and users can easily tweak the general settings without needing deep technical knowledge.

LiteSpeed’s extensibility is more limited compared to Varnish. Since LiteSpeed Cache is so closely tied to LiteSpeed Web Server, its capabilities are somewhat restricted to what the server allows. For example, while LiteSpeed supports object caching and dynamic content caching, it doesn’t offer the same modularity for external tools or custom-built solutions that Varnish does.

Feature richness

Below, we’ll list the key features of both caches to compare their richness and help you identify which one offers more capabilities for your architecture.

Varnish

• Customizable caching policies: Allows for fine-tuned control over caching based on HTTP headers, cookies, request methods, and more.
• Backend failover: If one backend server goes down, Varnish can switch to another backend to ensure high availability.
• Advanced cache purging: Offers precise cache purging methods, including purging specific objects, URLs, or even by tags, helping to keep the cache fresh and relevant.
• Support for large websites: Designed for high-traffic websites, Varnish can handle millions of requests per second, making it suitable for large-scale applications.
• Modular extensions: Can be extended with third-party modules to handle logging, SSL termination, and more.
• Cache invalidation on demand: Supports real-time cache invalidation based on changes in content, ensuring up-to-date content delivery.
• Enterprise-ready: Has enterprise version available for those needing advanced support or scalability.
• SSL/TLS: Provides secure encryption for cached content, protecting data in transit and maintaining compliance with security standards.
• Logging and statistics: Over 130 built-in performance metrics and over 100 lines of logs for every transaction.

LiteSpeed

• Built-in object caching: Supports caching of objects like database queries, which can reduce load on the database and speed up dynamic content.
• Page caching for dynamic content: Provides built-in support for caching dynamic content generated by PHP-based applications like WordPress.
• Automatic cache purging: Automatically purges cache when content is updated so that users always see the latest version of the site.
• Private and public caching: Supports both private and public caches, allowing sensitive content to be cached for individual users and public content to be cached for everyone.
• Browser cache management: Provides control over how browsers cache site resources, allowing for efficient use of client-side caching.
• Enterprise-ready: Has enterprise version available for those needing advanced support or scalability.
• LiteSpeed Web ADC (Load Balancer): Offers built-in support for LiteSpeed's load balancer to manage traffic across servers for optimized performance.
• CSS/JS minification: Automatically minifies CSS and JavaScript files, which reduces page load times.

Security features

Both Varnish Cache and LiteSpeed Cache offer some level of security features, but they differ in the types of controls provided. Let’s dive deeper below.

Varnish

• DDoS mitigation: Varnish can be configured to handle high traffic loads and mitigate DDoS attacks by rate-limiting requests and filtering suspicious traffic.
• ACLs (Access Control Lists): Allows administrators to define IP-based access rules to restrict or allow traffic, providing a layer of access control at the caching level.
• Backend health checks: Monitors backend servers to detect failures and switch to healthier backends. This feature prevents traffic going to compromised or failing servers.
• Custom security rules via VCL: Developers can use VCL to create custom security rules, such as filtering requests based on IP addresses, headers, or URLs, and blocking potentially malicious traffic.
• SSL/TLS termination (with third-party modules): While Varnish doesn’t natively handle SSL/TLS termination, it can work with third-party tools like Hitch to secure connections.

LiteSpeed

• Built-in SSL support: LiteSpeed Cache natively supports SSL/TLS for encrypted connections between users and the server.
• Brute force protection: Protects against brute force attacks by limiting login attempts, especially useful for WordPress and other CMS platforms.
• reCAPTCHA integration: LiteSpeed Cache integrates with Google reCAPTCHA to help prevent spam and bot traffic on login and comment forms.
• IP-based access control: Allows for IP whitelisting and blacklisting, which can be used to block unauthorized access at the server level.
• File permission hardening: Ensures strict file permissions to prevent unauthorized access to sensitive data.
• OWASP ModSecurity rules integration: Supports integration with ModSecurity, a popular web application firewall (WAF) that uses OWASP’s core rule set to protect against common vulnerabilities like SQL injection and cross-site scripting (XSS).

When to use which

Now that you have seen the comparisons between Varnish Cache and LiteSpeed Cache across several categories, it’s time for you to make an informed choice based on your specific needs and preferences. To help you with your decision, here is a breakdown of when to use which:

Use Varnish Cache:

• High-traffic websites and large enterprises: Varnish is designed for websites handling millions of requests per second. It’s ideal for large-scale applications with complex caching needs and high traffic volumes.
• Custom caching requirements: If your web app has very specific caching policies (e.g., caching based on cookies, headers, or URL patterns), Varnish’s VCL gives you the flexibility to define those.
• Edge Side Includes (ESI): If you need to cache parts of a web page while keeping certain sections dynamic, you can use Varnish ESI to do so.
• Backend failover and load balancing: When your application needs to distribute traffic across multiple backends or provide high availability through backend failover, Varnish’s built-in load balancing features can help.

Use LiteSpeed Cache:

• Using LiteSpeed web server: If your architecture uses LiteSpeed as the web server, then LiteSpeed Cache is the obvious choice for caching.
• WordPress and other CMS-driven websites: LiteSpeed Cache is the best option if you’re using popular CMS platforms like WordPress, Joomla, or Magento, as it offers seamless integration with dedicated plugins.
• Out-of-the-box caching: If you’re looking for a solution that doesn’t require a lot of configuration or technical expertise, LiteSpeed Cache is the way to go.
• SSL/TLS Support: LiteSpeed’s native SSL/TLS support makes it a great choice for web apps that need to handle encrypted traffic.
• Image optimization and CSS/JS minification: If you want built-in tools to optimize images and minify static assets, then you should go with LiteSpeed.
• Built-in security: For those who want a solution with advanced built-in security features like brute force protection, reCAPTCHA, and ModSecurity integration, LiteSpeed Cache is a better choice, as it offers a more comprehensive set of native security controls.
• Performance with minimal resources: If your web app is on a smaller server or shared hosting, then choose LiteSpeed Cache, as it is optimized for performance even in low-resource environments.

Conclusion

Varnish and LiteSpeed are both versatile caching solutions that can scale to handle high traffic volumes. As made evident by this comparative analysis, both have their share of strengths and weaknesses. Ultimately, the choice between the two depends on your individual needs with regards to performance, customizability, and interoperability.

Whichever platform you choose, remember to monitor its health and performance to ensure business continuity. Site24x7 offers monitoring tools for both Varnish and LiteSpeed.