Blacksmith raises $45M to fix AI coding's testing bottleneck
AI is writing code faster than teams can check it — and investors are betting that fixing that gap is the next big business in the AI coding boom.
Blacksmith, a startup that tests and validates software before it reaches production, has raised $45 million in a Series B led by Peak XV Partners, valuing the company at $550 million — nearly ten times the $60 million valuation it carried when it raised a $10 million Series A less than a year ago. Existing backers GV and Y Combinator joined the round, bringing Blacksmith's total funding to $58.5 million.
The round tracks a business growing almost as fast as its valuation. Blacksmith says revenue has grown more than tenfold over the past year, and its customer count has jumped from roughly 700 companies to more than 5,000, including Mercury, Supabase, Clerk, Ashby, and Expensify. The company reached a $10 million annualized revenue run rate with just 10 employees, has since grown its headcount to about 30, and now counts some of its largest customers spending more than $1 million a year.
The pitch is a response to the AI coding boom's side effect: tools like Cursor, OpenAI's Codex, and Claude Code make generating code easy, but the output still has to be verified. "Validating code is still a bottleneck, and it's an even bigger bottleneck because people are writing even more," co-founder and CEO Aditya Jayaprakash said. Blacksmith began as a cloud provider for continuous-integration workloads — the builds and tests that run before code ships — and has since added Codesmith, an agent that automatically fixes failed checks.
It is not alone in seeing the opportunity. GitHub Actions, Cursor Automations, and validation built into Codex and Claude Code compete for the same job, as do AI testing services from AWS, Microsoft Azure, and Google Cloud. Jayaprakash says Blacksmith differentiates on testing speed and price, and plans to expand from validation into a broader suite that helps developers write, merge, and ship code faster.
The bigger picture is that the AI coding gold rush is moving downstream. Generating code is getting commoditized; the durable value is in making agent-written code trustworthy enough to deploy. A nearly 10x valuation in under a year suggests the market is pricing that shift in early.
What to watch: whether the cloud giants fold enough validation into their own coding assistants to squeeze independent testers — or simply acquire them.
Would you trust an AI agent's code more if another AI verified it first? Tell us in the comments.
