Short answer: It depends.
When to Keep Category & Tag Pages
If your Category and tags have a lot of great content and match the searcher’s intent, it will be helpful and engaging to readers. Then you will want to keep them indexed.
An example of effective use of Category pages (Search Engine Land):
When to NoIndex Category & Tag Pages
It is imperative to avoid these common mistakes:
Duplicate Content: Using similar Categories and Tags in a single post. (e.g., tagging a post with: sell, sellers, selling, vendor, dealer, etc.)
Link Bloat: Tagging every page with a Category or Tag.
Thin Content: Having Categories or Tags with only one or two posts attached.
If you don’t have time to properly manage your Category and Tag hierarchy, noindex might be your best option. You might be rewarded for that if you have the time and resources.
Before you noindex your category and tag pages, check Google Analytics and Google Search Console to see if you receive organic traffic to those pages.
If you receive little to no traffic over a 6 to 12-month period, it is safe to noindex those pages.
If you’re looking for a way to keep your content helpful and informative for readers, consider your category and tag structure. By ensuring that they are both full of great content and closely match searcher intent, you can encourage people to stick around on your site longer – which means they’re more likely to see your product pages and buy what you’re selling. What tips do you have for creating good category and tag structures?