Rewriters

PageSpeed Service was turned off on August 3^rd, 2015. Please see Turndown Information for PageSpeed Service.

Overview

PageSpeed Service improves web page latency by changing the resources on that web page to implement web performance best practices. Each change that PageSpeed Service makes corresponds to a rewriter. The rewriters are applied in a pre-defined order on any resource being served by the service. Some basic optimizing rewriters are applied by default by PageSpeed Service (e.g. gzip, HTML cleanup etc.). Other rewriters that optimize CSS, images and JavaScript resources can be enabled and disabled in the Rewriter Settings pane of the Google APIs Console.

Here is the list of available rewriters in PageSpeed Service.

• HTML

  • Inline Small Resources
  • Optimize HTML
  • Proxy Resources

• CSS

  • Combine CSS
  • Flatten CSS Imports
  • Minify CSS
  • Move CSS to Head
  • Prioritize Critical CSS

• Images

  • Lazyload Images
  • Minify Images
  • Deduplicate Inlined Images

• JavaScript

  • Combine JavaScript
  • Defer JavaScript
  • Minify JavaScript

• Prioritize Content

  • Flush Resources Early
  • Pre-resolve DNS
  • Prioritize visible content
  • Cache and prioritize visible content
  • Partially Cache HTML

• Others

  • Add ETags
  • Measure Page Load Time
  • Shard Domains
  • Miscellaneous Features