Kiddle, a website billed as a "visual search engine for kids," was criticized on Twitter this week for blocking certain search terms as "bad words," including "gay," "puberty," "menstruation," and "child abuse." 

The website later removed the block on most of these words, instead showing links to articles on these topics aimed at children. 

Kiddle.co uses a custom Google search bar and the search giant's SafeSearch filter in its results, but is not affiliated with Google. 

From the site itself, it's not clear who is behind Kiddle, although the BBC reports that one of its early testers wrote that it was set up by the Russian founder of a site called Freaking News. 

Canadian author Robin Stevenson tweeted this week that the words "gay" and "lesbian" resulted in an error page calling the terms "bad words." 

Others on Twitter noticed other terms that brought up similar messages 

Kiddle later changed the results for some of these terms, but other search results remained blocked

By Wednesday, this message was also removed and users were shown results on the topic deemed appropriate for children 

Other users noticed some inconsistencies in what terms it allows and what it blocks. "Suicide" won't give you any results, but "self-harm" will. 

Kiddle is by no means the first search engine aimed at children. Some of the services, such as SafeSearchForKids.com block terms such a "gay," while others, such as GoogleJunior.com, do not.