Blacksmith Raises $66m Series C at $1bn Valuation

In August, investors valued Blacksmith at $550m. Ten weeks later, the start-up says Sequoia Capital has led a round that values it at $1bn.

Blacksmith runs continuous integration, or CI: the builds and tests that every code change has to pass before it can be merged. It announced on 21 October a $66m Series C led by Sequoia, with Premji Invest joining existing backers Peak XV Partners, GV and Y Combinator. The company puts its total funding at $125m. Its Series B, a $45m round led by Peak XV, was announced on 12 August at a $550m valuation.

The pitch is simple. AI coding tools have made writing code cheap, so the slow, expensive part is now checking it. “Developers who used to push three or four pull requests a day are now pushing orders of magnitude more and their CI infrastructure can’t keep up,” said Aditya “JP” Jayaprakash, Blacksmith’s co-founder and chief executive.

Ninety million jobs a week, by Blacksmith’s count

Blacksmith says the number of CI jobs it runs each week has grown from 5 million in January to more than 90 million, and that annual recurring revenue has grown 17-fold over the same period. It says more than 10,000 companies now use it, including Ashby, Granola, Handshake and LangChain, and that customers’ jobs finish twice as fast at 60% lower cost on average. None of these figures has been independently verified. Jayaprakash told Fortune, which first reported the round, that revenue is now “in the tens of millions” and that its largest customers spend more than $1m a year. Fortune says the customer count was about 5,000 in August.

Blacksmith’s release also cites Anthropic’s experience. In a September blog post, Anthropic said its CI jobs rose 25-fold over six months. It put that down to engineers shipping far more code, 80% of it written by Claude, and to a tenfold increase in tests.

Most of the money goes on machines

Most companies run CI on servers rented from AWS, Google Cloud or Microsoft Azure, Fortune notes. Blacksmith buys its own, tens of thousands of them according to Jayaprakash, and he told the magazine that most of the new money will go on more computing power. The company says it manages nearly 10MW of compute across data centres in the US and Europe and is on track to grow that at least fivefold in 2027.

Owning the machines cuts both ways. Jayaprakash told Fortune that it gives Blacksmith control over performance but exposes it to the industry-wide shortage of compute and memory, and that demand jumps each time a stronger model arrives. When Anthropic launched Claude Fable 5 in July, he said, CI volume on Blacksmith rose 40%.

The other risk is competition from the companies driving its growth. Fortune notes that coding agents such as Codex and Claude Code can already run a project’s tests, and that Microsoft-owned GitHub sells its own hosted machines for CI. Jayaprakash’s answer is that better models simply mean more code to check. “Usage on us actually goes up,” he said. A customer quoted in the release backs the cost case: Joaquin Borggio, an infrastructure engineer at LangChain, said Blacksmith had cut its runner costs “by roughly 40%”, not counting engineering time saved.

Blacksmith was founded in 2024 by Jayaprakash, Aayush Shah and Aditya Maru, who met at the University of Waterloo. Isaiah Boone, the Sequoia partner on the deal, said the founders “understood early that as AI agents wrote more code, the infrastructure to build and test it would need to change”. It is the second start-up selling plumbing for AI-written code to reach $1bn this week, after Daytona’s $60m round on Tuesday. Blacksmith has about 40 staff, Fortune reports, and plans to reach around 75 by the end of the year.