Blacksmith Reaches $1 Billion Valuation as Sequoia Leads $66M Series C for AI Code Testing Platform

Blacksmith Achieves Unicorn Valuation with $66M Series C Funding

Blacksmith has secured $66 million in Series C funding led by Sequoia Capital, propelling the AI code testing startup to a unicorn valuation of $1 billion1

1

2

2

. The round attracted participation from Premji Invest and existing investors Peak XV Partners, Google Ventures, and Y Combinator, bringing total funding to $125 million3

3

. This marks a dramatic acceleration for the company founded in 2024 by Aditya Jayaprakash, Aayush Shah, and Aditya Maru, with its valuation doubling in just two months from the $550 million it commanded during its $45 million Series B in August.

Explosive Growth Driven by AI-Written Code Surge

Blacksmith's platform addresses a critical bottleneck in software development: continuous integration, the automated process of building, testing, and validating code before deployment. The startup now serves more than 10,000 companies, up from approximately 5,000 in August2

2

. Weekly CI jobs processed on the platform have skyrocketed from 5 million in January to over 90 million, with the company running more than 90 million validation checks to date1

1

3

3

. This explosive demand has driven annual recurring revenue growth of 17x over the same period, with revenue now in the tens of millions and largest customers spending more than $1 million annually2

2

.

Why Continuous Integration Matters in the AI Era

AI code generation tools like Cursor, OpenAI's Codex, and Anthropic's Claude Code have fundamentally transformed how developers work. Co-founder and CEO Aditya Jayaprakash explained that developers previously spent half their time writing code and the other half waiting for builds and checks. AI coding tools have made writing code "extremely easy," but the bottleneck has shifted to validation2

2

. Jayaprakash emphasized in a blog post that "most companies are struggling to keep up with the volume of CI they need to run," particularly as AI agents write more software. "As agents write more of the world's software, the question that matters is whether it can be trusted," he noted1

1

.

Blacksmith's Infrastructure Advantage and Expansion Plans

Unlike competitors who rent servers from AWS, Google Cloud, or Microsoft Azure, Blacksmith owns tens of thousands of its own machines installed in data centers worldwide2

2

. The company writes its own software to run these machines, including systems that eliminate repetitive setup work each test would otherwise require. Currently managing nearly 10 MW of compute capacity across data centers in the United States and Europe, Blacksmith plans to expand total capacity by 5x in 2027 to meet growing enterprise demand3

3

. Most of the fresh capital will purchase additional compute capacity, according to Jayaprakash, who told Fortune that capacity planning remains one of the hardest aspects of the business as demand spikes with each new model release. When Anthropic launched Claude Fable 5 in July, CI volume on Blacksmith rose 40%2

2

.

Customer Base and Market Position

Blacksmith's customer roster includes high-growth tech companies Mercury, Granola, Supabase, LangChain, and Handshake1

1

2

2

3

3

. The platform is designed to absorb the unpredictable nature of CI demand with minimal operational overhead compared to general-purpose cloud infrastructure. With approximately 40 employees across San Francisco and New York, the company plans to grow to around 75 by year-end2

2

. Even leading AI labs face similar challenges—Anthropic reported its own validation workloads grew 25-fold in six months as Claude took over most code output2

2

.

Navigating Competition and Future Outlook

Blacksmith faces potential competition from AI model vendors who already focus heavily on coding products. Coding agents like Codex and Claude Code can run project tests as they work, and Cursor launched a product in March enabling companies to set up agents for automatic code review and testing. Microsoft-owned GitHub also sells hosted machines for running CI jobs2

2

. However, Jayaprakash argues Blacksmith complements what AI model companies do, since better models generate more code requiring validation. "Usage on us actually goes up," he stated. The startup's rapid valuation climb—from $60 million a year ago after a $10 million Series A to $1 billion today—signals investor confidence that software code building and testing infrastructure will remain critical as AI-written code becomes ubiquitous across the industry.