Speak, a language learning startup, has reached a US$1 billion valuation following a US$78 million funding round led by Accel.

Existing investors, including the OpenAI Startup Fund, Khosla Ventures, and Y Combinator, also participated.

The San Francisco-based startup has now raised a total of US$162 million.

With the latest funding, Speak plans to expand into Southeast Asia, Europe, and the United States.