I've seen HTML expand to 10x of course x3 and x4 was the most common! I think the page in question that was doing that was a php info page. Repetitive markup, as seen in the output of phpinfo , compresses very well.
The technical information in that output contains more direct repetition than the average chunk of natural language would too, and the alphabet distribution is probably less smooth which could help the Huffman stage get better results. This answer doesn't account for intentionally malicious compressed data. One can craft a malicious zip file around 10KB that can expand to a bit over 4GB. Zip bombs of that scale rely on nested archives though, so as a human unpacking the file you would noticed something odd before long.
They can be used as an effective DoS attack against automated scanners on mail services and so forth though. DavidSpillett: Nested zip bombs expand into sizes in the petabyte range. That's not what I'm talking about. Look at even just a single layer of a typical zip bomb.
Show 2 more comments. Wikipedia says Indeed, That is zip, not gzip — BeniBela. Community Bot 1. Here is an analysis at MaximumCompression , Look at one of the samples like, Summary of the multiple file compression benchmark tests File type : Multiple file types 46 in total of files to compress in this test : Total File Size bytes : NirIzr 4 4 bronze badges.
A huge file containing only one symbol will compress very well. Welcome to Super User! Please quote the essential parts of the answer from the reference link s , as the answer can become invalid if the linked page s change. It would be more accurate to say "frequency of each string" rather than "frequency of each character" — JoelFan.
The Overflow Blog. Does ES6 make JavaScript frameworks obsolete? Some proxies might cache gzipped resources without also caching their Content-Encoding, or even try to re-compress compressed content. The Vary HTTP response header specifies how proxies and caches handle compressed content and should be enabled whether dynamic or static compression is enabled. Before you can use static compression, you will need to create a gzipped copy of each file you want to serve.
To load the plugin, add the following line to your Apache configuration file:. As with Nginx, you can enable gzip for the entire web server or for a specific configuration block.
Apache also supports compression for certain file types, setting compression levels, and managing proxy settings. This example uses this method to serve pre-compressed CSS files:. To show the difference between compressed and uncompressed websites, we ran a page speed test on a website with three different configurations: one with compression enabled, one with compression completely disabled, and one serving only pre-compressed content.
We created a basic website using Hugo and hosted it on an f1-micro Google Compute Engine instance running Nginx version 1.
For the gzip-enabled versions, we used the default settings for both Nginx and the gzip command-line application. To run the test, we used a recurring page speed check to contact the site every 30 minutes.
After four runs, we reconfigured and restarted the Nginx server for the next test. We dropped the first run to allow time for the Nginx server to warm up. We verified that Nginx was using static compression and not dynamic compression by using strace to see which files were being accessed:. With dynamic compression, the web server transferred For some files, such as bootstrap.
Although this was a small site with few optimizations, simply enabling gzip on the web server allowed for a significant savings in load time. The fact that static compression performed roughly the same as dynamic compression also shows that for smaller sites, the cost of dynamic compression on system resources is minor.
Websites with larger files and higher traffic volumes will likely see a more significant amount of CPU usage, and would benefit more from static compression.
Gzip is a fast and easy way to improve page speed performance while still delivering a high-quality experience to your users. All other trademarks are the property of their respective owners. With Pingdom's website monitoring you are always the first to know when your site is in trouble, and as a result you are making the Internet faster and more reliable. Nice, huh? Gain availability and performance insights with Pingdom — a comprehensive web application performance and digital experience monitoring tool.
How, then, do we keep the internet fast? The solution, as you may guess, is that web servers compress files before sending them to browsers — they turn our page text document into more like a page essay. The reasoning is simple: smaller files mean less work that servers and browsers need to do to transfer them. Compression works well with code like HTML because its syntax is repetitive.
Compression algorithms generally work by finding repeated information in a file and abbreviating it somehow. GZIP is a compression technology frequently used for transferring data quickly over the internet. GZIP is the current standard for file compression on the web. For now, you just need to know why GZIP is often preferred over similar compression methods. Not bad, except tests comparing compressed file sizes across different compression algorithms have shown that alternative algorithms like Brotli outperform GZIP for text-based assets.
If this is true, why do we still rely so much on GZIP? The main reason is that GZIP tends to be faster than comparable methods. It compresses files in a fraction of the time that other methods take. This speed is crucial for data transfers over the web. Also important is the fact that GZIP compression uses fewer resources than comparable methods.
It requires relatively little computing power and temporary memory space to work. This is key when considering server space and the fact that half of global web traffic is mobile — GZIP is effective for sending web pages to high- and low-powered devices alike.
ZIP is another lossless compression format that is more often used for storing files than transferring them. For a file transfer to work with GZIP, two things must happen. First, the web browser tells the web server that it can accept GZIP-compressed files. Second, the web server processes this header and decides to either compress the requested files or leave them be. If the files are compressed with GZIP, the server includes the following header in its response:.
If you want your website files to be sent compressed, you must enable your server to handle GZIP requests. Here are a few ways to find out:. Some websites will also provide a brief report explaining how much GZIP reduced the file size:.
To check for GZIP compression without an external tool, you can use the developer tools panel in your browser. Most browsers let you inspect page elements and view performance information this way. First, load the web page you want to check in your browser. Then, open the developer tools panel and select the Network tab.
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