AI start-up Perplexity has raised US$500 million through a new funding round that values the OpenAI rival at around US$9 billion, according to reports.

VC investing giant Institutional Venture Partners led the funding round, which comes after a raft of new competing AI-based search engine launches in recent weeks.

OpenAI recently launched ChatGPT Search, its rival to Perplexity while Google reportedly is looking to incorporate some of the start-up's capabilities such as adding a chatbot-like "AI mode" into its search engine.

Google wins AI battle after blizzard of pre-Christmas launches

Like its rivals, Perplexity has had its share of controversy including accusations of plagiarism from news organisations, many of which it has now entered revenue-sharing deals, and a class action for copyright infringement.

Claiming to have at least 15 million users earlier in the year, Perplexity has kept ahead of its rivals using innovations such as a finance product that monitors share prices and earnings data using real-time information.

Reflecting its growth, Perplexity's value has rocketed this year compared to earlier funding rounds.

Valued at US$ 1 billion in April, this rose to US$3 billion in June when Softbank came on board as an investor and now has reached US$9 billion.

As well as Softbank, Perplexity boasts tech darling Nvidia and Amazon founder Jeff Bezos among its investors.

Like OpenAI's ChatGPT, Perplexity offers free-to-access and paid-for products.

Two days ago, the company also bought Carbon, a startup to link AI systems to external data sources.