Block, the company led by Jack Dorsey, has disclosed an internal AI coding system called Builderbot. The tool is now responsible for roughly 15% of the company’s production code changes, while performing about 200,000 operations per day and merging around 1,500 pull requests each week. The disclosure came four months after Block cut about 4,000 jobs in February.
Engineers can summon it in Slack and let it open pull requests
According to Block’s blog post, engineers use Builderbot by tagging @builderbot in Slack and describing a task in plain language. The system then researches the request, plans the work, writes code, and carries the task through a discussion thread. It can also pull tickets from Linear and Jira, create branches, submit pull requests, and revise its output based on team feedback.
Block said multiple team members can work with Builderbot in the same thread at the same time, watching progress as it happens and adjusting direction while the system is still working. That puts it closer to a workflow tool embedded in engineering operations than a simple code-completion assistant.
Block says the system understands a codebase spanning hundreds of services
The company drew a line between Builderbot and common AI coding assistants that operate within a single repository. Builderbot, Block said, can work across a broader internal environment that covers hundreds of services and hundreds of millions of lines of code. In practice, that allows an engineer focused on Cash App to make changes to other services they do not already know well, because Builderbot already understands how those systems operate.
Brad Axen, who leads AI capabilities at Block, said the best way to think about Builderbot is as the missing middle layer between AI coding tools and real large-scale engineering work. He said tasks that once took months can now be completed in days.
The announcement lands after layoffs tied by the company to AI acceleration
The timing also draws attention back to Block’s February layoffs. Jack Dorsey said at the time that the company would cut about 4,000 employees, reducing headcount from more than 10,000 to roughly 6,000, and directly linked the move to the acceleration brought by AI. The report added that by mid-April, code output per employee had reached 2.5 times the January level. Following the layoff announcement, Block shares at one point rose 24% in after-hours trading.
Block also said Builderbot is limited to source code and system configuration. It does not access customer data, payment information, or personally identifiable information. The system is built on top of Goose, Block’s open-source AI agent framework.