A war has begun between two popular dating app companies. Tinder’s parent company Match Group (NASDAQ: MTCH) has launched a lawsuit against Bumble for patent infringement and stealing trade secrets. The lawsuit claims that Bumble is virtually identical to Tinder and its only differentiating factor is that women make the first move.

The lawsuit cites trademark infringement and dilution, utility and design patent infringement, trade dress infringement, trade secret misappropriation, and unfair competition, amongst other claims. Tinder popularized the swipe right to like, swipe left to dislike functionality for which it has a federally registered trademark for use on computer application software for mobile devices. Match alleges that its utility patent gives Tinder the exclusive right to use to “a computer implemented method of profile matching.”

In the complaint, Match says, “This case is simply about forcing Bumble to stop competing with Match and Tinder using Match’s own inventions, patented designs, trademarks, and trade secrets.” In a statement, a Match Group spokesperson said the company is “committed to protecting the intellectual property and proprietary data that defines our business.”

Bumble, launched in 2014, has become a fierce competitor to Tinder. The company reportedly turned down a $450 million buyout offer from Match Group last year. According to reports, Match Group was still interested in Bumble’s business as recently as last November. In addition to Tinder, Match Group also owns dating sites OkCupid, Plenty of Fish, and Match.com.

Bumble’s co-creators are ex-Tinder employees. Bumble was launched by Whitney Wolfe Herd, who left Tinder in 2014 after alleging sexual harassment and discrimination. The case was eventually settled. Co-founders Chris Gulczynski and Sarah Mick are also ex-Tinder employees. Match Group asserts the three execs were able to replicate Tinder’s app because they “were given access to certain confidential information related to proposed Tinder features”.

Gulczynski and Mick are at the center of the stolen secret allegations. The company says that the two had knowledge of an “undo” button talked about at Tinder that is “nearly, if not literally, identical” to Bumble’s backtrack feature. The suit also claims that Gulczynski and Mick implemented photo messaging at Bumble after Gulczynski had designed the feature for Tinder. According to the Linkedin accounts for Gulczynski and Mick, both have left Bumble.