Blacked out homepages and links to petitions are greeting U.S. online visitors Wednesday, as several major websites protest anti-piracy legislation under consideration in the U.S. Congress.

Online encyclopedia Wikipedia blacked out its English language website for 24 hours, alongside blog Boing Boing. Social news website Reddit plans to go dark for part of the day, and popular search engine Google has replaced its normally colorful and interactive logo with a black censor bar.

These are just some of the online protests aimed at The Stop Online Piracy Act currently before the House of Representatives, and the Protect IP Act under consideration in the Senate. The measures are designed to crack down on the sales of pirated U.S. products overseas. The House bill currently includes a provision on blacklisting sites that contain pirated content.

Supporters of the legislation include the film and music industry, which often sees its products pirated illegally. The industry says the measures are needed to protect intellectual property and jobs.

Technology companies — such as Google and other Internet giants like Yahoo and Twitter — say the bills could hurt the technology industry and infringe on free speech rights if passed.

Last week, the White House acknowledged that online piracy by foreign websites is a serious problem that requires a serious legislative response. But the statement said, “we will not support legislation that reduces freedom of expression, increases cybersecurity risk or undermines the dynamic, innovative global Internet.”

The White House also said it will continue to work with Congress on a bipartisan basis on legislation to provide new tools needed in the global fight against piracy and counterfeiting, while defending free expression, privacy, security and innovation.