AI code testing startup ‘Blacksmith’ raises $45M in Series B

AI code-testing platform Blacksmith has raised $45 million in Series B funding at a valuation of $550 million, as the rapid adoption of AI coding tools creates a growing need for infrastructure that can test and validate software at much higher volumes. The round was led by Peak XV Partners, with existing investors Google Ventures (GV) and Y Combinator also participating. The latest financing brings Blacksmith’s total funding to $58.5 million.

The funding comes as software development is undergoing a major shift. AI coding agents are allowing developers to generate code and submit pull requests much faster, but every piece of generated software still needs to be built, tested and validated before it can reach production. Blacksmith is positioning its cloud infrastructure as a solution to this emerging bottleneck, while expanding into AI-powered tools that can help developers identify and fix problems in their code.

Blacksmith Raises $45 Million at $550 Million Valuation

The Series B represents a significant increase in Blacksmith’s valuation. The company was valued at around $60 million when it raised its previous $10 million Series A, meaning its valuation has increased more than ninefold in less than a year.

Funding Detail	Information
Company	Blacksmith
Latest Round	Series B
Amount Raised	$45 million
Lead Investor	Peak XV Partners
Existing Investors	GV, Y Combinator
Valuation	$550 million
Total Funding	$58.5 million
Previous Valuation	About $60 million
Headquarters	San Francisco
Customers	More than 6,000 companies

The sharp increase in valuation reflects investor confidence in the infrastructure required to support AI-assisted software development.

Blacksmith says its customer base has grown from approximately 800 companies around its previous funding round to more than 6,000. Customers include Supabase, Clerk, Ashby and Mercury.

AI Coding Creates a New Testing Bottleneck

The central idea behind Blacksmith’s business is relatively straightforward: AI can make software development faster, but faster code generation creates more work for testing systems.

AI coding tools can generate large amounts of code in a short period and allow developers to create multiple pull requests in less time. Those changes still have to pass automated builds and tests before they can be merged into production software.

Blacksmith co-founder and CEO Aditya Jayaprakash said teams using coding agents are generating several times more pull requests, making continuous integration increasingly important. The company says the number of continuous integration jobs running on its platform has increased by 5% to 10% every week since the beginning of 2026.

This creates a new infrastructure challenge for companies adopting AI coding at scale.

Why Continuous Integration Matters

Continuous integration, or CI, is the automated process through which software changes are built and tested before being merged into a larger codebase.

A typical CI workflow can run unit tests, integration tests, security checks and other automated validation processes whenever developers submit changes.

As AI agents generate more code, these workflows have to handle a substantially larger number of jobs.

That creates pressure on computing capacity, test execution times and infrastructure costs. Blacksmith’s strategy is to provide specialized cloud infrastructure designed specifically for these workloads.

Blacksmith Started With CI Infrastructure

Blacksmith originally focused on improving the infrastructure behind continuous integration rather than building an AI coding assistant.

Its platform runs GitHub Actions workloads on dedicated computing infrastructure and uses optimized caching and storage to accelerate software testing. The company says teams can migrate workloads with minimal changes to existing workflow configurations.

This approach allows Blacksmith to compete with established CI infrastructure from GitHub and major cloud providers while focusing specifically on speed and efficiency for software testing.

The company now manages hundreds of thousands of computing cores, according to information shared by Y Combinator. The new funding is expected to support a significant expansion of that infrastructure.

Blacksmith Expands Into AI Coding With Codesmith

Blacksmith is now moving beyond infrastructure and into AI-powered software development itself.

Its Codesmith product is designed to act as an AI coding agent that can help developers build features, investigate bugs and diagnose failed CI checks.

The company is also developing capabilities that can automatically fix certain problems identified during validation. Its longer-term goal is to have AI systems test changes autonomously before those changes are merged into production code.

This expansion gives Blacksmith an opportunity to participate in more stages of the software-development lifecycle.

Instead of simply providing the computing infrastructure required to test code, the company can potentially help developers generate, validate and fix that code through the same platform.

Funding Will Expand Compute Capacity

Blacksmith plans to use much of the new capital to expand its computing infrastructure.

The company already operates hundreds of thousands of CPU cores, and Y Combinator said the infrastructure is expected to grow by roughly 10 times in the coming months.

The investment is important because AI-generated software can create substantially higher testing workloads.

If a developer using an AI agent generates several times more code than before, the infrastructure supporting that development process must also scale accordingly. Blacksmith believes this creates an opportunity to become an important layer between AI-generated code and production software.

The company is also expected to expand its engineering presence in New York and San Francisco.

Revenue Has Also Scaled Rapidly

Blacksmith’s growth has extended beyond customer numbers.

Y Combinator said the company reached a $10 million annualized revenue run rate with just 10 employees and has since grown revenue into the tens of millions of dollars. Some of its largest customers are spending more than $1 million annually on the platform.

The figures highlight how valuable software-development infrastructure can become when it is embedded into enterprise engineering workflows.

For Blacksmith, the opportunity is particularly significant because CI infrastructure can become deeply integrated into a company’s development process. Once a platform is responsible for running thousands or millions of automated tests, switching providers can involve technical, financial and operational considerations.

Peak XV Bets on AI Infrastructure

Peak XV Partners led the Series B, giving the venture capital firm a significant position in a company benefiting from the rapid expansion of AI-assisted development.

The investment reflects a broader trend in venture capital: AI is creating opportunities not only for companies developing foundation models and coding assistants, but also for infrastructure providers that support those systems.

Blacksmith is targeting one of the less visible but increasingly important parts of the AI software stack.

AI can generate code quickly, but businesses cannot simply deploy every piece of AI-generated code without testing it. As a result, tools that improve the speed and reliability of software validation could become increasingly important.

Competition Is Increasing

Blacksmith operates in a market that includes established platforms such as GitHub Actions and infrastructure provided by AWS, Microsoft Azure and Google Cloud.

It also faces a longer-term competitive challenge from AI coding companies that may decide to build their own testing and validation capabilities.

The company therefore needs to demonstrate that specialized infrastructure can deliver enough performance and cost advantages to justify adopting another layer in the development stack.

Its growing customer base and rising CI workloads suggest there is already demand for faster validation, but maintaining that growth will require continued investment in computing capacity and product development.

The Bigger Shift in Software Development

Blacksmith’s funding highlights a broader change taking place across the software industry.

For years, the main productivity challenge was helping developers write code faster. AI coding assistants have significantly reduced that bottleneck. The challenge is now increasingly moving downstream.

Once code can be generated quickly, organizations need systems capable of reviewing, testing, securing and deploying that code just as efficiently.

This creates opportunities across the software-development infrastructure market. Testing, observability, security, deployment and quality assurance could all become more important as AI increases the volume of software being produced.

Blacksmith is betting that code validation will be one of the biggest beneficiaries of this shift.

Looking Ahead

Blacksmith’s $45 million Series B gives the company substantial capital to expand the computing infrastructure behind its platform while building a broader suite of AI-powered development tools. Its growth from roughly 800 customers to more than 6,000, alongside rapidly increasing CI workloads, suggests that AI-generated code is already creating measurable demand for faster validation infrastructure.

The larger opportunity will be determining whether Blacksmith can become a critical layer in the AI-native software-development stack. If coding agents continue to increase the volume of software produced by engineering teams, the ability to test and validate that code quickly could become just as important as the ability to generate it. Blacksmith’s expansion from CI infrastructure into AI coding and autonomous testing puts the company in a position to capture more of that emerging workflow.