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We first saw news of the petition on The Daily Dot.
Recently, Tumblr blocked users from searching for blogs posted under hashtag categories like #NSFW (Not Safe For Work), #Gay, #Porn, and so on.
Also at play: Many in the Tumblr community are still upset Yahoo bought the blogging network, and see the blocked "NSFW" searches as the first sign of a big scary corporate entity noodling around with an established independent online community in order to make a few extra bucks.
In a post on the company's staff blog, Tumblr CEO David Karp attempted to clear up why Tumblr is blocking adult content from searches. He said app stores like Google and Apple don't allow pornographic content in their apps, so blocking such searches on the iPhone and Android apps saves Tumblr from being pulled from those app stores.
Karp has a point. Apple has been especially vigilant about removing apps that make it easy to find pornographic content, even if that content is user-generated. Most recently, Twitter's video app Vine had to block searches for categories like porn and sex so it could stay in Apple's App Store.
And finally, there's a small concession from Tumblr. The service has simplified its "NSFW" settings so blogs won't appear if someone is browsing the site in Tumblr's "safe mode," which automatically filters out adult content.