As both established companies and emerging players race to seize opportunities in artificial intelligence, numerous AI startups are reporting not just revenue growth, but accelerating revenue growth, hitting key milestones in increasingly shorter timeframes. The startups listed below have demonstrated this kind of flywheel effect. It's worth noting that the specific metrics these companies use vary, even when they all refer to "ARR." Some define it as annualized recurring revenue—revenue under contract from paying customers but not yet billed. Others mean annualized run-rate revenue, which projects annual income by taking the most recent month's revenue and multiplying it by 12. Still others use "committed ARR," referring to signed contracts from customers who haven't yet been onboarded. In Gusto's case, the company reported actual trailing 12-month revenue. Regardless of the definition, each of these startups—listed in reverse chronological order based on when their ARR growth was made public—reports that their revenue growth is accelerating, however they define it. Of course, there are many more fast-growing AI startups beyond those named here, but this list focuses specifically on companies hitting revenue milestones at ever-faster rates.

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**Mercor:** On Monday, Brendan Foody, co-founder and CEO of Mercor, announced that the company has surpassed $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 it achieved a $500 million run rate in September.

**Anthropic:** In recent months, this model maker's revenue has grown at such a historic pace that it has captivated the entire AI industry. In late May, Anthropic announced it had crossed $47 billion in revenue run rate, a milestone that came less than two months after the company reported the same metric had 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 it had 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 demonstrates 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.