Google has updated the Googlebot help document on crawling to clarify that the 15MB fetch size limit applies to each fetch of the individual subresources referenced in the HTML as well, such as JavaScript and CSS files.
Google initially added information about this 15MB limit several months ago, which caused a lot of concern in the SEO industry, so make sure to read that story.
The help document now reads:
Googlebot can crawl the first 15MB of an HTML file or supported text-based file. Each resource referenced in the HTML such as CSS and JavaScript is fetched separately, and each fetch is bound by the same file size limit. After the first 15MB of the file, Googlebot stops crawling and only considers the first 15MB of the file for indexing. The file size limit is applied on the uncompressed data. Other Google crawlers, for example Googlebot Video and Googlebot Image, may have different limits.
It previously read:
Googlebot can crawl the first 15MB of an HTML file or supported text-based file. Any resources referenced in the HTML such as images, videos, CSS, and JavaScript are fetched separately. After the first 15MB of the file, Googlebot stops crawling and only considers the first 15MB of the file for indexing. The file size limit is applied on the uncompressed data. Other Google crawlers may have different limits.
Gary added on LinkedIn, "PSA from my inbox: The 15MB resource fetch threshold applies on the JavaScript resources, too, so if your JavaScript files are larger than that, your site might have a bad time in Google Search. See googlebot.com for information about the fetch features and limitations. Yes, there are JavaScript resources out there that are larger than 15MB. No, it's not a good idea to have JavaScript files that are that large."
Here are some comments on early feedback from the SEO community on this:
Are you running into 15mb Don size? That's quite a bit.
— johnmu is not a chatbot yet 🐀 (@JohnMu) March 19, 2023
The 15mb is just about fetching, it's totally separate from the indexing side.
— johnmu is not a chatbot yet 🐀 (@JohnMu) March 19, 2023
Forum discussion at LinkedIn.
