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."

The new Kiddle search engine tells kids that "gay" and "lesbian" are "bad words." So NOT okay. <a href="https://t.co/Wtvxejn6Kn">pic.twitter.com/Wtvxejn6Kn</a> —@robin_stevenson

A kids' search engine that lets kids search "genocide" but not "puberty," "gay" or "transgender" is useless. <a href="https://t.co/6FNl0b6WqM">https://t.co/6FNl0b6WqM</a> —@robin_stevenson

Others on Twitter noticed other terms that brought up similar messages

Kiddle. It's like Google for kids! Filters out all the nasty words like, er... <a href="https://t.co/wW7xguiqIk">pic.twitter.com/wW7xguiqIk</a> —@wordgeeksez

[cw child abuse] OK this search engine is actually dangerous, this is the worst thing kids seeking help should hear <a href="https://t.co/yBbDBISBMh">pic.twitter.com/yBbDBISBMh</a> —@stavvers

I don’t know if Kiddle launched prematurely, but this is just asinine. cc <a href="https://twitter.com/robin_stevenson">@robin_stevenson</a> <a href="https://t.co/bTR8rj06FH">pic.twitter.com/bTR8rj06FH</a> —@RobCottingham

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

Oh it's even better now. Please ask your homophobic parents about homosexuality <a href="https://t.co/TnPegZgU4B">pic.twitter.com/TnPegZgU4B</a> —@LuigiThirty

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

<a href="https://twitter.com/urwalder">@urwalder</a> WOW. A kid can search info on puberty and periods and actually get useful info instead of being told off! Glad they're listening! —@robin_stevenson

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.