Blacksmith, a San Francisco startup that runs continuous integration (CI) infrastructure for software teams, has raised a $66 million Series C led by Sequoia Capital at a $1 billion valuation. The round lands about two months after Blacksmith raised a $45 million Series B led by Peak XV Partners at a $550 million valuation in August.
Premji Invest joined the Series C alongside existing investors Peak XV Partners, GV and Y Combinator, bringing Blacksmith's total funding to $125 million. The company said it will use the money to grow its team and expand compute capacity.
Blacksmith's pitch rests on a shift in where software bottlenecks sit. With AI coding agents producing a large and growing share of code, the company argues the hard part has moved from writing code to validating it, and CI is where that validation happens. Its announcement cites Anthropic, which reported its CI volume grew 25x in six months as Claude took over most of its code output.
“Developers who used to push three or four pull requests a day are now pushing orders of magnitude more”— Aditya Jayaprakash, Co-founder and CEO of Blacksmith
Key facts
- 01Blacksmith raised a $66M Series C led by Sequoia Capital at a $1B valuation, announced October 21, 2026.
- 02The valuation is up from $550M at its $45M Series B, led by Peak XV Partners in August.
- 03Weekly CI jobs on Blacksmith grew from 5 million to more than 90 million since January; ARR grew 17x.
- 04More than 10,000 companies run CI on Blacksmith, including Ashby, Granola, Handshake and LangChain.
- 05Total funding stands at $125M; the company plans to grow its ~10 MW of compute at least 5x in 2027.
The usage numbers track that shift. Blacksmith said weekly CI jobs on its platform grew from 5 million to more than 90 million since January, and annual recurring revenue grew 17x over the same stretch. CEO Aditya Jayaprakash has put revenue in the tens of millions of dollars.
More than 10,000 companies now run CI on Blacksmith, including Ashby, Granola, Handshake and LangChain. The company started 2026 with roughly 800 customers and had about 5,000 by August. Earlier customers include Mercury, Supabase, Clerk and Expensify.
The product is built as a drop-in replacement. Customers switch by changing one line in their workflow file, and Blacksmith takes over provisioning, scaling and maintaining CI infrastructure. Jobs run on Firecracker microVMs on bare-metal, gaming-grade CPUs as an alternative to GitHub Actions' default cloud runners.
Blacksmith says customer CI jobs run about twice as fast at 60% lower cost on average. LangChain infrastructure engineer Joaquin Borggio said Blacksmith reduced the burden of managing the company's CI runners and cut its runner costs by roughly 40%.
Jayaprakash founded Blacksmith in January 2024 with Aayush Shah and Aditya Maru. The three met at the University of Waterloo, previously worked on distributed systems at Faire and Cockroach Labs, and went through Y Combinator's Winter 2024 batch.
“What stood out to us was their deep systems expertise and speed of execution.”— Isaiah Boone, Partner at Sequoia Capital
Blacksmith manages nearly 10 megawatts of compute across the US and Europe and said it plans to grow that capacity at least fivefold in 2027.
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