DeepSeek, a Hangzhou-based startup founded in 2023, shot to the top of Apple’s App Store free app chart after releasing a new open-source AI model it says rivals OpenAI's work. Its website was hit by outages amid a spike in interest.

Entrepreneur Marc Andreessen, known for co-writing Mosaic, one of the world’s first web browsers, wrote Sunday on X that “DeepSeek R1 is AI’s Sputnik moment,” likening it to the space race between the U.S. and the Soviet Union and the event that forced the U.S. to realize that its technological abilities were not unassailable.

DeepSeek is just one of an array of companies developing AI models and applications. Here’s a guide to a number of the biggest players in China.