Brotli Compression Algorithm

Every byte matters, especially when you pay for it. The most popular lossless compression utility Gzip has been around since 1992. The need for more modern algorithms emerged, which is why in 2016 CDN77 has become the first CDN provider to support Brotli.

Anything that makes your content delivery faster and cheaper is a high priority for us. That’s why we now offer the Brotli support for free to all clients. If you are our customer, there is no need to activate the functionality, it’s ON by default. You can find a list of automatically compressed formats in our knowledgebase.

How to test Brotli?

You can see enabled compression algorithms by checking the content-encoding response header. Streams compressed with Brotli have the content-encoding type "br".

Brotli and CDN77

Brotli is a compression algorithm introduced in September 2015 by Google. Our tests confirm that Brotli should bring 25% reduction in data size compared to Gzip for the most common assets like Javascript and CSS files. Those results were in line with experiments made by both and Akamai. For HTML, Brotli promises up to 40% difference (with median around 25%).

According to the official website, in addition to the dynamically populated ("sliding window") dictionary, Brotli uses a pre-defined dictionary of over 13000 common words, phrases and other substrings. This allows for greater compression ratio on files/bitstreams that contain them.

While deploying, we even found a bug in the code, but the awesome guys from the Chrome development team fixed it at an amazing speed. So even thanks to them you can enjoy Brotli in Chrome. Nowadays it's supported in all major browsers. If Brotli is not applicable for your use case, gzip is still an option we can offer.

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