Is Google AMP Cache a free CDN service?

Question

I know Google AMP Cache caches valid AMP pages and resource files of a website and make them available via .cdn.ampproject.org/. I made some tests and it works fine for my website.

I work for a popular website with terabytes of throughput per day. What happens if I make all my image files available via google AMP Cache? Will AMP Cache just serve my files for free?

Is this a free CDN service? If it is free, why are companies paying for CDN services?

My boss just don't buy the idea that google AMP cache is a free CDN. He asks "what if the service is discontinued abruptly?" or "what if they start to charge the throughput?". Is there any gotcha?

Does anyone know about a big company currently using the AMP Cache as a CDN?

Answer 1

Using the Google AMP Cache for serving images for display outside of documents served from the Google AMP Cache is not a supported use and may not work, or may stop working in the future.

[Tech lead of AMP here]

Answer 2

Does anyone know about a big company currently using the AMP Cache as a CDN?

Just to calm your boss, AMP pages is being used by prestigious online publishers around the world including The Atlantic, The Washington Post, Vox Media, BuzzFeed, The Guardian and The New York Times and Twitter as well.

But I'm concerned if there are limits on bytes transferred or number of client requests. - The batchGet method has a default limit of 50; request up to 50 AMP URLs each time you call this method. This is found in AMP Usage Limits.

Answer 3

You can use AMP cache for contents on your AMP pages for free, there is a limitation on size, from FAQ:

Are there size limits on resources?

Yes, the Google AMP Cache does not fetch any resources (i.e., HTML, images, fonts) that are larger than 12 MB. In these cases, the Google AMP Cache returns a 404 error.