Blacksmith Hits $1B: $66M to Test the Code AI Agents Write

There is a new unicorn in developer infrastructure, and it sells something deeply unglamorous: testing. Blacksmith, a startup building a dedicated cloud for continuous integration, announced a $66 million Series C on October 21, 2026, led by Sequoia Capital. The Blacksmith Series C funding round values the company at $1 billion, with total funding now at $125 million.

The round landed just two months after a $45 million Series B led by Peak XV Partners that valued the company at $550 million. A year ago, Blacksmith raised a $10 million Series A at a $60 million valuation. That is a 16x valuation jump in twelve months, the kind of trajectory that usually belongs to model companies, not infrastructure for running test suites.

Inside the Blacksmith Series C funding round

Sequoia led the round, with participation from Peak XV Partners, Y Combinator, GV, and Premji Invest. The speed of the markup tells the story investors are buying: the Series B to Series C step took two months and nearly doubled the valuation. When a company raises twice in a quarter at those multiples, the lead investor is usually racing someone else to the term sheet.

Blacksmith was founded in 2024 by co-founder and CEO Aditya Jayaprakash, reportedly alongside Aayush Shah and Aditya Maru, University of Waterloo alumni. Two years from founding to unicorn is fast by any standard; in infrastructure, where sales cycles are measured in quarters, it is remarkable.

What Blacksmith actually sells

Continuous integration is the machinery that builds, tests, and validates every code change before it merges: the unsexy pipeline that stands between a developer's commit and production. Most companies run CI on general-purpose cloud servers, sharing compute with everything else in the cloud.

Blacksmith's pitch is a "CI cloud": dedicated hardware and software built specifically for running CI workloads. The argument is that CI has distinct performance characteristics (bursty, parallelizable, latency-sensitive in the developer-feedback sense) and deserves purpose-built infrastructure rather than rented general compute. It is the same specialization logic that gave us GPU clouds for AI training, applied to the humble test suite.

The bet: agents write code, someone has to test it

CEO Aditya Jayaprakash framed the moment plainly: "As agents write more of the world's software, the question that matters is whether it can be trusted." That is the entire thesis. AI coding agents are generating code at a volume humans never could, and every line of it still needs to be built, tested, and validated. The more code agents write, the more CI gets run. Blacksmith is selling shovels to the agent gold rush.

The numbers back the narrative. Annual recurring revenue has grown 17x. The company has run over 90 million CI jobs. Its customer base grew from roughly 700 companies at the Series A to more than 5,000 by the Series B, and customers include Mercury and Granola, two companies with engineering cultures picky enough that their logos carry weight.

Why CI is suddenly interesting

Developer infrastructure has been quietly absorbing the agent wave all year. Vercel open-sourced Durable Harness to make coding agents survive crashes, agent-focused funding like Mural's $15M round keeps landing, and models like Recursive's Flint are being built by AI themselves. Blacksmith sits one layer below all of that, in the unglamorous plumbing that determines whether agent-written code is trustworthy.

That positioning is why Sequoia paid up. Model capabilities are commoditizing fast; the durable businesses in the agent era may be the ones that verify, test, and govern what the models produce. Trust infrastructure is a good place to be when everyone is worried about whether the code can be trusted.

The risk is the obvious one: hyperscalers could decide CI deserves purpose-built infrastructure too, and they have deeper pockets and existing relationships. But Blacksmith's growth suggests developers are happy to buy from a specialist when the specialist is meaningfully faster. In infrastructure, speed is a feature, and right now Blacksmith is selling the fastest shovels in the gold rush.