April 4 (Bloomberg) — Mozilla Corp., maker of the Firefox Web browser, said Chief Executive Officer Brendan Eich resigned after being criticized for donating money to an anti-gay marriage group.

Eich, who also co-founded Mozilla, became CEO in March. The controversy concerned a $1,000 donation he made in 2008 to a group that supported Proposition 8, a California initiative that banned same-sex marriage and was later found to be unconstitutional.

While Eich said in interviews in recent days that he wouldn't resign for expressing a personal opinion, he changed his mind, according to a blog post yesterday by Mitchell Baker, Mozilla's executive chairwoman. She didn't name a replacement for Eich, and said there will be more information next week.