Yes. Ad libraries are published deliberately by the platforms as public transparency tools. The data is public by design, viewing it requires no account relationship with the advertiser, and studying competitor advertising is ordinary market research that every serious marketing team does.
The question people are usually really asking is a different one, so it is worth separating.
Looking is not the risk. Copying is.
What you can freely do is read a competitor's ads, note their offers, study which creative formats they keep running, and draw conclusions about their strategy. Facts, prices, formats and strategies are not protected.
What creates genuine exposure is reproducing their actual assets: lifting their photography, video, illustrations or copy verbatim, using their trade marks or logos in your own advertising, or reproducing a distinctive campaign so closely that it misleads people about who they are dealing with. Those are copyright and trade mark questions, and they do not depend on where you found the material.
Why copying is a bad idea even when it is lawful
A competitor's best ad is tuned to their brand, their audience, their price point and their proof. Strip all of that away and what remains is a format, which is the least valuable part.
The useful output of competitor research is never a copied ad. It is an understanding of why something works: which objection it defuses, which promise it leads with, which format that message needs. Then you build your own version. Our breakdown of how HelloFresh structures its ads is what that looks like end to end.
On terms of service
Reading an ad library in a browser is exactly what it is published for. Bulk automated scraping is governed by each platform's terms, which is a separate consideration from legality and one reason tools in this space use official APIs and licensed data sources rather than scraping.
This is general information, not legal advice. If you are planning something close to a competitor's distinctive creative, ask a lawyer in your jurisdiction.