The move comes just a week after the Chinese startup DeepSeek unveiled its R1 artificial intelligence model, a rival to U.S. leaders like OpenAI and Anthropic that boasted far lower development costs. While the launch continues to reverberate through the tech world, spurring the chipmaker Nvidia to lose $600 billion in market cap, one clear winner has emerged: open-source software like Goose. Where companies like OpenAI favor a closed model, DeepSeek makes its underlying code public, meaning other developers can use and modify it.

The surprise breakout of DeepSeek has brought the debate over open versus closed-source development into the forefront, with software engineers and tech leaders long arguing over the best approach to advance innovation. Jack Dorsey, the head of Block and former Twitter CEO, took the opportunity to make his own preferences clear. “Open source everything,” he posted on X on Monday.

Block’s open-source ambitions

Dorsey has long been a champion of open-source development, with Block working on landmark projects like the cross-computer gRPC communication protocol, and his company is doubling down on the approach. Last Tuesday, Block announced the opening of its Open Source Program Office, which will house five engineers who help work across the company’s suite of products, including Cash App, Square, and Tidal.

Today’s launch of Goose allows users to connect with large language models like OpenAI’s o1 or DeepSeek’s R1 to perform real-world tasks, from checking code for bugs to sending emails.

In an interview with Fortune, Block’s open-source lead Manik Surtani said the approach is the “best way to build software.”

“It’s even more important for a financial services company to be building on open principles and open standards,” he said. “That is what everyone really wants. They want transparency.”

Codename Goose

While AI platforms like ChatGPT represent the first major consumer breakthrough, so-called “agents,” or tools that allow AI to perform tasks on behalf of users, represent the next frontier for the technology, allowing programs that can do anything from booking travel to managing stock portfolios.

Goose is the first project out of Block’s new dedicated open-source office. Surtani said the technology first came out of engineers building a tool to help them write software, but they realized its potential to perform other types of tasks, like organizing calendars or sending emails. Unlike other AI agents, which are typically closed-source and designed for specific functions, Block created Goose with the capability to interact with different LLMs and expand beyond its original purpose.

“Anyone can add to it and extend it,” Surtani told Fortune. “Proprietary agents can only work within what it was designed by its creators [to do].”

Surtani, who has worked at Block for 11 years, said that the company has long advocated for open-source development because it allows for more collaboration between developer communities, as well as more consumer choice, with Dorsey being a strong proponent for the approach.

Still, open-source tools are rare in financial services, often due to security and privacy concerns, though Surtani argued it’s a misconception that open-source programs (like the Linux operating system) are less secure.

Surtani said the long-term goal for Block is to expand choice for consumers, such as open banking, which would allow customers to move money and accounts between different financial institutions easily: “Those things don’t actually exist at this stage.”

With the success of DeepSeek, AI development could see a paradigm shift toward a more open-source approach—a trend that Surtani said is already in motion. “We want open by default to be a North Star,” he told Fortune.