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As companies old and new rush to capitalize on AI, many AI startups say that their revenue is not just growing, but rapidly accelerating, hitting their next milestones in shorter timeframes.

The following list of startups have reported a pattern of such flywheel growth. One thing to note is that the underlying metrics used by these companies differ, even if they are using the term “ARR.” Some may be referring to annualized recurring revenue (ARR), or revenue under contract from a paying customer but not yet billed. Some are referring to annualized run-rate revenue, or projecting annual income by calculating 12 months of revenue that continues at the rate of the most recent month. Others are referring to “committed ARR,” or signed contracts from customers that are not onboarded yet. In the case of Gusto, it reported actual trailing 12-month revenue.

Nevertheless, each of these startups, listed in reverse chronological order to when their ARR growth was made public, reports that their revenue growth is accelerating, however they are defining it. To be sure, there are many more fast-growing AI startups than we’re naming here, but we are limiting this list to the companies hitting revenue milestones at ever-faster rates.

Mercor: On Monday, Brendan Foody, co-founder and CEO of Mercor, announced that the company has crossed $2 billion in gross annualized revenue as of June — just four months after reaching the $1 billion milestone. The less-than-three-year-old firm, which hires domain experts to train and refine AI models, said that it reached a $500 million run rate in September.

Anthropic: In recent months, this model maker’s revenue has been at such a historic velocity that it has mesmerized the entire AI sector. In late May, Anthropic announced that it crossed $47 billion in revenue run rate, a milestone that came less than two months after the company reported that the same metric surpassed $30 billion. The company said it reached a $9 billion revenue run rate in late 2025, up from a reported $4 billion in July 2025.

Sierra: After reaching its first $100 million in ARR in seven quarters, Sierra—which builds customer service AI agents for enterprises — says it took just two more quarters to add another $100 million, co-founder and CEO Bret Taylor announced in late May.

Glean: In May, Glean announced that it crossed $300 million in ARR. While it took the seven-year-old enterprise AI startup nine months to double its ARR from $100 million to $200 million, the company says it needed just six months to grow that metric from $200 million to $300 million.

Gusto: The 14-year-old HR tech startup announced in May that its revenue accelerated in each of the last five quarters. The company, which was last valued at $9.3 billion in early 2022, also reported that it surpassed $1 billion in trailing 12-month revenue. Gusto’s revenue surge shows that it’s not only AI-native companies that are seeing their top-line growth supercharged by integrating the technology.

Clio: This 18-year-old provider of legal practice management software saw its revenue take off sharply after embedding AI into its offering in 2023.  The company surpassed $200 million in ARR in mid-2024, doubled that figure by late last year, and recently announced that its ARR reached $500 million.