How to Check What is Inside Sitecore HTML Cache?

It is a copy of this blog post.

Sitecore has a lot of caches: AccessResultCache, DataCache, DeviceItemsCache, HTML cache, ItemCache, ItemPathsCache, PathCache, RegistryCache, RuleCache, StandardValuesCache, ViewStateCache, XslCache, FieldReaderCache and others. When you facing with caching issue on your website(something is either not cached, or cached but should not), it is important to have the ability to see what is present in cache.

All Sitecore caches consist of cache key and cache value. Cache key is always string. Cache value could be any type of object depending on cache. We can take as example HtmlCache cache. When you see what cache key you have and what data is there, you can better tune caching of controls, especially when you have custom(not out of the box) cache criterias (vary by IP, vary by country, vary by role, etc.) and a lot of controls on a page. Here is code snippet to get everything inside HtmlCache:
It requires using reflection due to private methods in HTML cache. The result of execution GetCaches method will be List<Tuple<string, string>>, that you can filter, make search or display on the page. It can save you a lot of time when debugging Sitecore caching issues. Here is an example of service page that displays cache keys and cache values:

If you can’t add this code to some secure page in your solution(you don’t want to do it or need some out of the box solution) then there are also other useful tools for troubleshooting issues with Sitecore cache. But they will not show you the cached value of HtmlCache entry:

• Sitecore Cache Admin - marketplace module.
• Sitecore Rocks - Visual studio extension for Sitecore. Cache viewing option is available from Sitecore 8.2.