As AI makes coding dramatically faster, the next big challenge in software development is testing and validating all that code. Blacksmith has raised a new $45 million round to capitalize on that shift.

The Series B, led by Peak XV Partners, values Blacksmith at $550 million, up from the $60 million valuation it was assigned when it raised a $10 million Series A less than a year ago. Existing investors GV and Y Combinator also participated, bringing the startup’s total funding to $58.5 million.

Founded in 2024, Blacksmith helps companies build, test, and verify software before it reaches production. The startup now serves more than 5,000 customers, including Mercury, Supabase, Clerk, Ashby, and Expensify, up from more than 700 customers less than a year ago, co-founder and CEO Aditya Jayaprakash said in an exclusive interview.

The rise of AI coding tools such as Cursor, OpenAI’s Codex, and Anthropic’s Claude Code has made it significantly easier for software teams to generate code, but the quality of AI-generated code is not a given.

“Validating code is still a bottleneck, and it’s an even bigger bottleneck because people are writing even more,” Jayaprakash said.

Blacksmith started as a cloud provider for continuous integration (CI) workloads, helping companies run the software builds and tests needed to validate code before it reaches production. The startup has since broadened its platform with Codesmith, an AI coding agent that can automatically fix failed code checks.

Jayaprakash said Blacksmith reached a $10 million annualized revenue run rate with just 10 employees and has since grown its workforce to about 30 and grown revenue to “tens of millions of dollars.” He declined to provide a specific updated ARR figure, though did say some of its largest customers now spend more than $1 million a year on the platform.

While that appears to be solid and fast progress, Blacksmith is operating in a crowded market. Its key competitors include GitHub Actions, Cursor Automations, validation capabilities baked into Codex and Claude Code, numerous other startups, and AI code-testing services offered by Amazon Web Services, Microsoft Azure, and Google Cloud.

Jayaprakash said his startup is competing on the speed of testing code as well as affordability.

Looking ahead, Jayaprakash said that Blacksmith plans to expand into a broader suite of coding tools, aiming to help developers write, validate, and merge software faster.