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Introduction
Would you like to disable certain Fasterize optimizations to diagnose behavior or test a debug hypothesis?
Good news: you can do this easily, without changing the overall configuration, simply by adding parameters to the URL.
In this article, we explain how to disable (or enable) rules, either temporarily or permanently, and how to adjust certain advanced options.
Disable a rule for a specific page
To disable a rule only on the URL you are visiting, use the following syntax:
?frz-[rule]=false
- Example:
?frz-lazyload=false - This disables lazy loading only for this page.
- Useful for testing behavior without impacting other pages
💡 You can also write ?frz-[rule]=true to force activation if necessary.
Persistently disable a rule (via session cookie)
Certain rules apply to resources loaded in subrequests (images, scripts, fonts, etc.).
In this case, adding the parameter to the main URL is not sufficient, as it will not be passed on to linked resources.
To disable a rule on all requests in the session, use the following form:
?frz-persist-[rule]=false
- Example:
?frz-persist-compressimgs=false - This creates a session cookie that is sent with all requests.
- The cookie is valid for 24 hours.
💡 To verify that the cookie has been set correctly, open the Application tab in DevTools, under Cookies.
Disable all Fasterize optimizations
If you want to see how a site behaves without any Fasterize optimization, you can disable all rules at once:
?frz-optimize=false
- This is equivalent to deactivating all active modules.
- Convenient for comparing with the "raw" version of the site
Disable a specific option in a rule
Some Fasterize rules have advanced options that you can also manipulate via the URL.
Syntax:
?frz-[rule]-[option]=value
Some examples:
?frz-compressimgs-jpg-quality=70→ custom JPEG quality?frz-compressimgs-png-convertPng24toPng8=false→ disables 24-bit PNG conversion?frz-lazyload-offset=3→ ignore the first 3 images?frz-google_fonts-fontDisplayValue=swap→ adjusts the behavior of Google fonts
💡 These settings are very useful for quickly testing a configuration hypothesis without reconfiguring the site in the interface.
List of available rules and settings
Rules that can be disabled via ?frz-[rule]=false
- frz-lazyload
- frz-concatcss
- frz-concatjs
- frz-deferjs
- frz-inlining
- frz-cssontop
- frz-resourcesversioning
- frz-preloading
- frz-google_fonts
- frz-responsive
- frz-service-worker
- frz-minifyhtml
- frz-unsherding
- frz-edge_rewriter
- frz-unlazyload
- frz-early-hints
Rules with session cookies (?frz-persist-[rule]=false)
- frz-persist-optimizefont
- frz-persist-compressions
- frz-persist-minifycss
- frz-persist-minifyjs
Examples of options that can be disabled
- frz-deferjs-onlyexternal
- frz-minifyhtml-keepcomment
- frz-compressimgs-jpg-active
- frz-compressions-jpg-quality
- frz-compressions-jpg-progressive
- frz-compressimgs-jpg-stripMetadata
- frz-compressimgs-jpg-automaticQualityDetection
- frz-compressimgs-jpg-automaticQualityPreset (low, medium, high, very high)
- frz-compressimgs-png-convertPng24toPng8
- frz-lazyload-offset
- frz-lazyload-version
- frz-google_fonts-fontDisplayValue
- frz-google_fonts-asyncLoad
Conclusion
Fasterize URL parameters are valuable allies for:
- Testing the behavior of an optimization
- Diagnosing a bug or side effect
- Easily compare different versions of a page
They allow you to remain independent in your testing, without depending on a global configuration change.
💡 Consider opening a private browsing window or clearing your cookies to start with a clean slate.