How to Compress an HTML File

As your website grows to include more customized, interactive content, the HTML volume increases exponentially. The result? Potential problems on both the server and client end of the website. That’s where compressing HTML files comes into the picture.

This post will walk you through what you need to know about compressing HTML files. You’ll learn the difference between compression and minification, how to start compressing HTML files, and your options.

• What’s the difference between compressing HTML and minification?

• Why Compress an HTML File?

• How to Compress an HTML File

• Options for Compressing HTML Files

• Things to Avoid While Compressing HTML

• Keep it Small, Keep it Simple

What’s the difference between compressing HTML and minification?

When considering ways to make your HTML files smaller, you probably hear two terms tossed around: Compression or minification. And while there is some overlap between the two (namely, they can both be used to reduce the total size of an HTML file), they’re not interchangeable. This is because they use distinctly different methods to achieve their goal.

Minification removes unnecessary lines and characters in source HTML code. As a result, you reduce the total file size and don’t impact the function of the code itself. While first-generation minification tools made users manually remove redundant code, new, automated solutions streamlined the process.

Compressing HTML is different. While the file size shrinks, redundant code is replaced with references attached to the original information. This indicates the position of the duplicated data, which is called “lossless compression.” Therefore, when you compress HTML instead of minifying it, you don’t experience any data loss, but you get a smaller file.

Lossless compression identifies repeated words, phrases, or characters, eliminates them, and creates numbered reference points tied to their first instance in the file. This allows decompression tools to reconstruct the original format.

Here’s an important distinction: While compression and minification deliver similar output file sizes, compressed files usually cannot be used in their shrunk-down format. Instead, they’ll have to decompress before delivering essential functions.

Why Compress an HTML File?

At this point, you may be wondering why compressing HTML files is a feasible solution in the first place. There are two primary benefits. Compressing HTML files can improve your website speed and reduce bandwidth use. Here’s why those are so important.

Improve Website Speed

Consider a website using substantial amounts of HTML code. Whenever a new visitor lands on your site, their browser makes an HTTPS request for specific pages, which are then located and sent back to the browser.

More HTML code means bigger pages, meaning end-users take longer to receive the completed page. And we all know what a slow page load time means — frustrated visitors. If you use HTTP protocol-compliant HTML compression utilities, your web server can compress the page before it leaves your server.

As a result, your user’s browser will decompress the page when it arrives, enhancing overall speed. Yes, this requires extra CPU power on the server side, but modern hosting solutions can typically accommodate this additional resource use. We think it’s a worthwhile trade-off.

Bandwidth

As for bandwidth, compressing HTML can help reduce the amount of traffic moving from your web server to end-users by a massive amount — up to 90 percent. And with the cost of web hosting often tied to network traffic — some hosts offer packages with set data transfer limits and penalties for going over, while others use on-demand pricing — the smaller your HTML files, the less data you’re sending. And you know what that means: The less you’ll spend every month.

How to Compress an HTML File

Ready to get started compressing HTML? As noted above, the usual form of HTML compression is “lossless,” meaning no data is lost throughout the process but modified to reduce total size. Here’s how it works.

Consider this line of text: “hello hello hello hello”

Compression algorithms can recognize the repetition in our example line and identify the first instance of the word “hello” as a reference. It leaves this reference alone and uses the first letter of the second “hello” instance as a reference marker to yield this:

“hello h{ello h}{ello h}ello”

Then, it recognizes the reference text is six characters behind and six characters long:

“hello h[6,6]{ello h}ello”

Additionally, it identifies the second repetition of another six characters and how the last four characters are the same as first four reference characters to yield a much smaller final product:

“hello h[6,16]”

Options for Compressing HTML Files

So, you want to compress your HMTL files but don’t know where to begin. If you’re looking to get started, there are two choices: You can use a free or premium application and do it yourself. Alternately, you can leverage in-browser options to automatically compress HTML data before sending it to end-users.

In nearly all cases, the second option is better for your business and your website since you won’t need to worry about either side of the equation — data is compressed when it leaves your web server and decompressed when it reaches its destination.

Of course, there are occasions where manual compression makes more sense. For instance, suppose you’re currently in the development phase of website design or are focused on optimizing your site to gain more traffic. In that case, you may not have high enough bandwidth requirements to justify spending on hosting packages that include in-browser compression. It’s also worth testing differing compression options to determine which offers the best balance of speed, size, and simplicity.

As noted above, the most common compression tool currently used by web hosts is gzip, which uses the familiar HTTP protocol to automatically compress HTML files from your web server and decompress them on end-user devices. Worth noting?

Not every hosting provider uses gzip — or any HTML compression. Consider other options if your current or prospective web host doesn’t use compression. Alternatively, you can ask them to integrate some form of compression to boost speed and reduce file size.

Things to Avoid While Compressing HTML

While there are plenty of perks associated with compressing HTML, there are some potential shortcomings you should be aware of.

The first one is potential security concerns. If you’re using a company such as gzip through HTTPS, if there are any security flaws, your website could experience some issues. As a result, files that have sensitive information could be exposed or in trouble. For this reason, you should avoid compressing file types with sensitive information with gzip.

Next, compression might not be the right choice if your file is under a specific size. If your file is just a couple of bytes, compression could be counteractive, so watch out.

Next, be cautious that you’re not over-compressing your files. There’s usually not that significant of a difference in file size regardless if you choose to normally or heavily compress your file.

Lastly, be sure you’re not compressing files that are already compressed. Recompression could also prove counteractive and could result in a larger file. Alternatively, it could take up a significant amount of memory.

Keep it Small, Keep it Simple

The smaller, the better for HTML files, especially when it comes to website optimization. Here, compression is critical to improve page loading times and limit overall bandwidth use, in turn delivering the dual benefits of reduced hosting costs and enhanced end-user experience.

Editor's note: This post was originally published in December 2020 and has been updated for comprehensiveness.