- Blacksmith raised $66M in Series C funding led by Sequoia Capital at a $1B valuation.
- The valuation nearly doubles the $550M set by its Series B, announced in August.
- More than 10,000 companies run their software builds and tests on its platform.
Every code change a developer proposes, known as a pull request, has to be built and tested before it ships. AI coding agents have multiplied the number of changes, and San Francisco-based Blacksmith runs those tests for other companies. It has raised $66 million in Series C funding at a $1 billion valuation.
Sequoia Capital led the round. Bengaluru-based Premji Invest, the family investment arm of Wipro founder Azim Premji, joined existing investors Peak XV Partners, GV, Alphabet’s venture arm, and Y Combinator.
The round takes Blacksmith’s total funding to $125 million. The money will go toward hiring and computing capacity: Blacksmith manages just under 10 megawatts across data centres in the US and Europe and plans to grow that fivefold in 2027.
“Since Claude Code took off in March, almost every conversation we’ve had with a large engineering team has started the same way. 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. We’re grateful to our customers who are trusting us to solve this bottleneck, and excited to partner with Sequoia to solve it at scale,” said Aditya Jayaprakash, co-founder and CEO of Blacksmith.
The bottleneck in software has moved from writing code to checking it. Anthropic said in a September 14 blog post that the number of continuous integration (CI) jobs in its own codebase rose 25-fold in six months, with Claude writing 80% of its code. CI jobs are the automated builds and tests that run on every proposed change, and running them is Blacksmith’s business.
Three Waterloo friends building code validation
Jayaprakash founded Blacksmith with Aayush Shah and Aditya Maru, all computer science graduates of the University of Waterloo. Shah and Maru were friends from their first semester, and Shah and Jayaprakash met on a co-op placement, according to the university.
Jayaprakash previously built search and advertising systems at wholesale marketplace Faire. Shah and Maru worked at database company Cockroach Labs, whose chief executive, Spencer Kimball, is an angel investor in Blacksmith.
The startup, founded in 2024, works by running customers’ CI jobs on servers it buys and operates itself, rather than on general-purpose cloud machines. For teams that use GitHub Actions, GitHub’s built-in automation tool, switching takes a one-line change to a workflow file, the company says. Blacksmith also says developers on its platform finish CI jobs twice as fast and at 60% lower cost on average.
Customers include Mercury, Granola, Handshake, and LangChain.
Steep growth and undisclosed revenue
Weekly CI jobs on the platform have grown from 5 million in January to more than 90 million, and annual recurring revenue has grown 17-fold, Blacksmith says. It has not disclosed the revenue itself.
The customer base has grown with it: about 800 companies when Blacksmith announced its Series A in September 2025, more than 6,000 at its Series B in August, and more than 10,000 at the Series C.
The price has moved faster than the disclosures. Blacksmith’s $10 million Series A, led by GV and announced in September 2025, valued it at $60 million, according to TechCrunch. The $45 million Series B, led by Peak XV, valued it at $550 million. Blacksmith closed that round in March but announced it on August 12, then announced the Series C 10 weeks later. The $1 billion price is nearly 17 times the Series A valuation and almost double the Series B figure.
Peak XV is the former Sequoia Capital India and Southeast Asia business, which became independent in 2023, so Blacksmith’s last two lead investors share a lineage.
“JP and team understood early that as AI agents wrote more code, the infrastructure to build and test it would need to change. What stood out to us was their deep systems expertise and speed of execution. That has translated into a product that helps their customers test and ship their software faster. We believe that foundation gives Blacksmith room to build much more as the demands of software development change,” said Isaiah Boone, partner at Sequoia Capital.
Sequoia is also an investor in LangChain, one of Blacksmith’s named customers, and led Whop’s $205 million round at a $5.1 billion valuation, as Tech Funding News reported. Peak XV also backs Supabase, which Blacksmith named as a customer in August.
A crowded field, with GitHub and the AI labs as rivals
Blacksmith operates in a crowded market. TechCrunch listed GitHub Actions, Cursor Automations, validation features inside OpenAI’s Codex and Anthropic’s Claude Code, and the testing services of AWS, Microsoft Azure, and Google Cloud among its rivals. Jayaprakash said the startup competes on speed and price. He has also said that owning its hardware gives Blacksmith better control over its costs than the large cloud providers have.
Blacksmith had about 30 employees in August, and is hiring in New York and San Francisco.
Others are placing similar deals on the machinery around AI agents. Daytona, which builds sandboxes for them, reached the same $1 billion valuation on October 20, and Modal raised $750 million at a $15.75 billion valuation on October 14.
The open question is whether the business of checking AI-written code stays independent or gets absorbed by the platforms where agents already work.
