What is GZIP compression?

GZIP is a compression algorithm that reduces file size during transfer between server and browser. It can reduce text file sizes (HTML, CSS, JavaScript) by 60 to 80%.

What is Brotli compression?

Brotli is a newer compression algorithm than GZIP, developed by Google. It offers better compression (15-20% better than GZIP) and is supported by all modern browsers since 2016.

How to enable GZIP compression on Apache?

To enable GZIP on Apache, you need to enable the mod_deflate module and add the configuration to your .htaccess or httpd.conf file. The complete guide with ready-to-use configurations is available in this article.

How to enable GZIP compression on Nginx?

To enable GZIP on Nginx, add the 'gzip on;' directive to your nginx.conf file with the MIME types to compress. Nginx includes GZIP support by default, you just need to enable it.

How to verify if GZIP compression is active?

You can verify GZIP compression with the online tool CheckGzipCompression.com, or by using your browser's DevTools (Network tab) to see the 'Content-Encoding: gzip' header.

What is the difference between GZIP and Brotli?

GZIP is older and compatible with all browsers, offering 60-80% reduction. Brotli is newer, offers 70-90% reduction (15-20% better than GZIP) but requires additional configuration. It's recommended to enable both: Brotli as priority with GZIP as fallback.

Does server compression replace minification?

No, compression and minification are complementary. Minification optimizes source code by removing spaces and comments. Compression then compresses the minified file for additional gain during network transfer. Both techniques together offer the best results.

GZIP and Brotli Compression: Complete Guide for Apache and Nginx

Why enable server compression?

Server compression is one of the most effective and simplest optimizations to implement. Unlike minification which optimizes source code, compression reduces file size during transfer between server and browser. Combined with minification, it can reduce your total file size by 70 to 90%, drastically improving load times and user experience.

70-90% reduction in transferred file sizes

50-70% improvement in load times

Substantial savings on bandwidth and hosting costs

Better score in Google's Core Web Vitals

Optimized user experience, especially on slow connections

Real-world impact of compression on performance

Concrete performance metrics

Here are real data from an e-commerce site that enabled GZIP compression:

Chart showing performance improvement after enabling compression

Before optimization

File size:2.5 MB

Load time:1.2s

After optimization

File size:380 KB

Load time:0.3s

Improvements

85% reduction in transferred size (from 2.5 MB to 380 KB)

75% improvement in load time (from 1.2s to 0.3s)

85% savings on bandwidth

Significant improvement in LCP (Largest Contentful Paint)

Impact on SEO and Core Web Vitals

Compression directly improves your web performance metrics:

LCP (Largest Contentful Paint): -40 to -60% thanks to smaller files

FID (First Input Delay): -30% thanks to less data to parse

CLS (Cumulative Layout Shift): Reduced reflows

TTI (Time to Interactive): -50% waiting time

What is server compression?

Compression vs Minification: Understanding the difference

Minification and compression are two complementary but different techniques. Minification removes spaces, comments and optimizes source code. Compression (GZIP or Brotli) then compresses the already minified file for additional gain during network transfer.

Imagine your file is a suitcase. Minification is removing everything unnecessary from the suitcase. Compression is using a compression machine to make the suitcase even more compact before sending it. Both techniques together offer the best results.

1. Write your JavaScript or CSS code normally

2. Minify the code (40-80% reduction)

3. Compress the minified file with GZIP/Brotli (additional 60-80% reduction)

4. Result: final file 5 to 10 times smaller than the original

GZIP vs Brotli: Which compression to choose?

GZIP is the most widespread compression and compatible with all browsers. Brotli is newer and offers better compression (15-20% better than GZIP), but requires additional configuration.

GZIP

compression:60-80% reduction

compatibility:100% of browsers

cpu:Low CPU consumption

setup:Simple configuration

Brotli

compression:70-90% reduction

compatibility:All modern browsers (2016+)

cpu:Slightly higher CPU consumption

setup:More complex configuration

Recommendation: Enable both! Configure Brotli as priority, with GZIP as fallback for older browsers.

GZIP Configuration on Apache

Method 1: Enable via .htaccess (recommended for beginners)

The simplest way to enable GZIP on Apache is to use the .htaccess file. This method works even if you don't have access to the main server configuration.

Create or modify the .htaccess file

# Enable GZIP compression
<IfModule mod_deflate.c>
  # Compress HTML, CSS, JavaScript, Text, XML and fonts
  AddOutputFilterByType DEFLATE text/html
  AddOutputFilterByType DEFLATE text/css
  AddOutputFilterByType DEFLATE text/javascript
  AddOutputFilterByType DEFLATE text/plain
  AddOutputFilterByType DEFLATE text/xml
  AddOutputFilterByType DEFLATE application/javascript
  AddOutputFilterByType DEFLATE application/x-javascript
  AddOutputFilterByType DEFLATE application/json
  AddOutputFilterByType DEFLATE application/xml
  AddOutputFilterByType DEFLATE application/xhtml+xml
  AddOutputFilterByType DEFLATE application/rss+xml
  AddOutputFilterByType DEFLATE application/atom+xml
  AddOutputFilterByType DEFLATE image/svg+xml
  AddOutputFilterByType DEFLATE font/ttf
  AddOutputFilterByType DEFLATE font/otf
  AddOutputFilterByType DEFLATE font/woff
  AddOutputFilterByType DEFLATE font/woff2
  
  # Don't compress already compressed images
  SetEnvIfNoCase Request_URI \.(?:gif|jpe?g|png|webp)$ no-gzip dont-vary
  SetEnvIfNoCase Request_URI \.(?:exe|t?gz|zip|bz2|sit|rar)$ no-gzip dont-vary
</IfModule>

Verify that mod_deflate module is enabled

# To verify, run this command on your server:
apache2ctl -M | grep deflate

# If the module is not listed, enable it with:
sudo a2enmod deflate
sudo systemctl restart apache2

Method 2: Configuration in httpd.conf (for advanced users)

For a more global and performant configuration, configure GZIP directly in Apache's main configuration file.

Configuration

# In /etc/apache2/apache2.conf or /etc/httpd/httpd.conf

# Enable deflate module
LoadModule deflate_module modules/mod_deflate.so

# Compression configuration
<IfModule mod_deflate.c>
  # Compression level (1-9, 6 is a good compromise)
  DeflateCompressionLevel 6
  
  # MIME types to compress
  AddOutputFilterByType DEFLATE text/html text/plain text/xml text/css
  AddOutputFilterByType DEFLATE text/javascript application/javascript
  AddOutputFilterByType DEFLATE application/json application/xml
  AddOutputFilterByType DEFLATE application/xhtml+xml application/rss+xml
  AddOutputFilterByType DEFLATE image/svg+xml
  AddOutputFilterByType DEFLATE font/ttf font/otf font/woff font/woff2
  
  # Exclude already compressed files
  SetEnvIfNoCase Request_URI \.(?:gif|jpe?g|png|webp|ico|gz|zip|bz2|rar)$ no-gzip
  
  # Exclude files that are too small (less than 1 KB)
  DeflateFilterByType text/html text/plain text/xml text/css text/javascript application/javascript
</IfModule>

After modifying httpd.conf, restart Apache with: sudo systemctl restart apache2 (or httpd depending on your distribution)

Brotli Configuration on Apache

Installing mod_brotli module

Brotli requires installing an additional module. Here's how to install it depending on your system.

Installation on Ubuntu/Debian

# Install dependencies
sudo apt-get update
sudo apt-get install -y libbrotli-dev

# Install mod_brotli from sources
# Download from: https://github.com/kjdev/apache-mod-brotli
# Or use PPA if available

Enable the module

# Enable the module
sudo a2enmod brotli
sudo systemctl restart apache2

Brotli configuration in .htaccess

Once the module is installed, configure Brotli in your .htaccess with priority over GZIP.

Configuration

# Brotli configuration (priority over GZIP)
<IfModule mod_brotli.c>
  # Compression level (1-11, 6 is recommended)
  BrotliCompressionLevel 6
  
  # MIME types to compress
  AddOutputFilterByType BROTLI_COMPRESS text/html text/plain text/xml text/css
  AddOutputFilterByType BROTLI_COMPRESS text/javascript application/javascript
  AddOutputFilterByType BROTLI_COMPRESS application/json application/xml
  AddOutputFilterByType BROTLI_COMPRESS application/xhtml+xml application/rss+xml
  AddOutputFilterByType BROTLI_COMPRESS image/svg+xml
  AddOutputFilterByType BROTLI_COMPRESS font/ttf font/otf font/woff font/woff2
  
  # Exclude already compressed files
  SetEnvIfNoCase Request_URI \.(?:gif|jpe?g|png|webp|ico|gz|zip|bz2|rar)$ no-brotli
</IfModule>

# GZIP configuration as fallback
<IfModule mod_deflate.c>
  AddOutputFilterByType DEFLATE text/html text/css text/javascript application/javascript application/json
</IfModule>

The browser will automatically choose Brotli if it supports it, otherwise it will use GZIP.

GZIP Configuration on Nginx

Basic configuration in nginx.conf

Nginx includes GZIP support by default. You just need to enable it in your configuration.

Configuration

# In /etc/nginx/nginx.conf (global configuration)
# Or in your specific site file

# Enable GZIP compression
gzip on;
gzip_vary on;
gzip_proxied any;

# Compression level (1-9, 6 is recommended)
gzip_comp_level 6;

# MIME types to compress
gzip_types
    text/plain
    text/css
    text/xml
    text/javascript
    application/json
    application/javascript
    application/xml+rss
    application/atom+xml
    image/svg+xml
    font/ttf
    font/otf
    font/woff
    font/woff2;

# Minimum file size to compress (1 KB)
gzip_min_length 1000;

# Don't compress already compressed files
gzip_disable "msie6";

After modification, test the configuration with: sudo nginx -t then restart with: sudo systemctl restart nginx

Optimal configuration for production

Advanced configuration to maximize performance in production.

Configuration

# Optimal GZIP configuration for Nginx
gzip on;
gzip_vary on;
gzip_proxied any;
gzip_comp_level 6;
gzip_buffers 16 8k;
gzip_http_version 1.1;

gzip_types
    text/plain
    text/css
    text/xml
    text/javascript
    application/json
    application/javascript
    application/xml+rss
    application/atom+xml
    image/svg+xml
    font/ttf
    font/otf
    font/woff
    font/woff2;

gzip_min_length 1000;
gzip_disable "msie6";

# Cache compressed files
gzip_static on;

gzip_static allows serving pre-compressed files (.gz) if they exist, further improving performance.

Brotli Configuration on Nginx

Installing ngx_brotli module

Nginx requires installing the ngx_brotli module. Here's how to proceed.

Installation from sources

# Install dependencies
sudo apt-get update
sudo apt-get install -y libbrotli-dev

# Download ngx_brotli
cd /tmp
git clone https://github.com/google/ngx_brotli.git
cd ngx_brotli
git submodule update --init

# Recompile Nginx with the module (requires Nginx sources)
# Consult the official documentation for complete details

Installation via package (if available)

# On some distributions, ngx_brotli is available via package
# Check with your package manager

Brotli configuration in nginx.conf

Once the module is installed, configure Brotli with GZIP as fallback.

Configuration

# Brotli configuration (priority over GZIP)
brotli on;
brotli_comp_level 6;
brotli_types
    text/plain
    text/css
    text/xml
    text/javascript
    application/json
    application/javascript
    application/xml+rss
    application/atom+xml
    image/svg+xml
    font/ttf
    font/otf
    font/woff
    font/woff2;

brotli_min_length 1000;

# GZIP configuration as fallback
gzip on;
gzip_vary on;
gzip_comp_level 6;
gzip_types text/plain text/css text/javascript application/javascript application/json;
gzip_min_length 1000;

The browser will automatically choose Brotli if it supports it (modern browsers), otherwise GZIP will be used.

Verify that compression is working

Use an online verification tool

The simplest way to verify if GZIP or Brotli compression is active on your site is to use a specialized online tool.

Compression verification tool interface showing results

GiftOfSpeed Gzip/Brotli Test

Free and simple tool to verify GZIP and Brotli compression of your website

https://www.giftofspeed.com/gzip-test/

Features:

•Instant GZIP compression verification
•Brotli compression detection
•Display of original vs compressed size
•Reduction percentage displayed
•Test on multiple resources (HTML, CSS, JS)

How to use:

1. Visit https://www.giftofspeed.com/gzip-test/

2. Enter your website URL

3. Click 'Test webpage'

4. Review the results: you'll see if GZIP/Brotli is active and the reduction percentage

Manual verification with browser DevTools

You can also verify compression directly in your browser's development tools.

Open DevTools

Press F12 or Cmd+Option+I (Mac) / Ctrl+Shift+I (Windows/Linux)

Network tab

Go to the 'Network' tab and reload the page

Check headers

Click on a resource (HTML, CSS, JS) and look at the 'Headers' tab. You should see 'Content-Encoding: gzip' or 'Content-Encoding: br' (Brotli)

Example

# Example response header with GZIP compression
HTTP/1.1 200 OK
Content-Type: text/css
Content-Encoding: gzip
Content-Length: 15234

# Example response header with Brotli compression
HTTP/1.1 200 OK
Content-Type: text/css
Content-Encoding: br
Content-Length: 12345

Best practices and recommendations

Which files to compress?

Compress text files, but avoid compressing already compressed files.

Compress:

HTML, CSS, JavaScript

JSON, XML, SVG

Fonts (TTF, OTF, WOFF, WOFF2)

Text files (TXT, CSV)

Don't compress:

Already compressed images (JPEG, PNG, GIF, WebP)

Binary files (PDF, ZIP, EXE)

Video and audio files

Already compressed files (.gz, .bz2)

Optimal compression levels

Find the right balance between size and CPU consumption.

GZIP level 6: Good compromise for most sites

Brotli level 6: Optimal for Brotli (better compression than GZIP level 6)

Avoid level 9: Marginal gain for significant CPU consumption

Level 1-3: For servers with limited CPU resources

Minimum file size

Don't compress very small files, the gain is negligible.

Configure a minimum size of 1 KB (1000 bytes). Smaller files will not be compressed, saving CPU resources.

Cache and compression

Combine compression and caching for optimal performance.

Serve pre-compressed files (.gz, .br) when possible

Configure appropriate Cache-Control headers

Use ETags for cache validation

Enable compressed file caching in Nginx (gzip_static)

Common troubleshooting

Compression is not working

If compression doesn't seem active, check these points:

Verify that mod_deflate (Apache) or gzip (Nginx) module is enabled

Check server error logs for error messages

Make sure MIME types are correctly configured

Verify that the browser sends the 'Accept-Encoding: gzip, br' header

Test with an online tool like GiftOfSpeed Gzip/Brotli Test

Apache configuration errors

Common problems with Apache and their solutions.

Errors and solutions

# Error: 'mod_deflate' not found
# Solution: Enable the module
sudo a2enmod deflate
sudo systemctl restart apache2

# Error: Syntax error in .htaccess
# Solution: Check the syntax, each line must be correct

Nginx configuration errors

Common problems with Nginx and their solutions.

Errors and solutions

# Error: 'unknown directive "gzip"'
# Solution: Check that you don't have a typo
# gzip must be written exactly like this

# Error: Configuration test failed
# Solution: Test with sudo nginx -t to see exact errors

Conclusion

Enabling GZIP and Brotli compression on your Apache or Nginx servers is an essential optimization that can drastically reduce the size of your transferred files. Combined with minifying your JavaScript and CSS code, compression can significantly improve your website performance, reduce your bandwidth costs and improve your Google ranking thanks to better Core Web Vitals.

Enable GZIP first (compatible with all browsers)

Add Brotli if possible for even better compression

Configure a minimum size of 1 KB to avoid compressing small files

Test regularly with GiftOfSpeed Gzip/Brotli Test to verify everything works

Combine compression and minification for optimal results

Monitor impact on your Core Web Vitals in Google Search Console

Ready to optimize your files?

Try our minification tool now

GZIP and Brotli Compression: Complete Guide for Apache and Nginx — Reduce Your File Size by 70-90%

Why enable server compression?

Real-world impact of compression on performance

Before optimization

After optimization

Improvements

What is server compression?

GZIP

Brotli

GZIP Configuration on Apache

Create or modify the .htaccess file

Verify that mod_deflate module is enabled

Configuration

Brotli Configuration on Apache

Installation on Ubuntu/Debian

Enable the module

Configuration

GZIP Configuration on Nginx

Configuration

Configuration

Brotli Configuration on Nginx

Installation from sources

Installation via package (if available)

Configuration

Verify that compression is working

GiftOfSpeed Gzip/Brotli Test

Features:

How to use:

Open DevTools

Network tab

Check headers

Example

Best practices and recommendations

Compress:

Don't compress:

Common troubleshooting

Errors and solutions

Errors and solutions

Conclusion

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