Why Anthropic Really Bought Bun

Oven, the company behind the JavaScript runtime Bun, had raised roughly $26 million in venture funding and still generated zero revenue. 

Despite that, usage continued to climb—Bun’s monthly downloads grew 25% in October, crossing 7.2 million. 

“When people ask, ‘Will Bun still be around in five or 10 years?’, answering with ‘We raised $26 million’ isn’t a great answer. Investors eventually need a return,” the company stated. 

Recently, Bun was acquired by the AI lab Anthropic for an undisclosed amount.

The company also made it clear that it still had a four-year runway and did not need to join Anthropic to survive. 

However, it no longer wished to drag its users and contributors through the uncertainty of finding a monetisation model. 

“Thanks to Anthropic, we can skip that chapter entirely and focus on building the best JavaScript tooling,” the company said.

Developer Value & Strategic Fit

Anthropic’s dependence on Bun changed the trajectory. “Claude Code ships as a Bun executable to millions of users. If Bun breaks, Claude Code breaks,” Bun stated. Anthropic made the same point, adding that Bun had been “central to the rapid execution of the Claude Code team”. 

The two groups had been working together long before the acquisition, and the deal simply aligned the incentives.

For years, developers were reaping the benefits of Bun’s performance. Adithya S Kolavi, an AI researcher and founder of CognitiveLab, told AIM, “I have done a few projects on the Bun runtime, and in my experience, it is fast. You really notice it in startups, local development and how easily it handles a large number of requests without much tuning.”

“It just feels smoother than what you get with the usual Node setup,” he added. 

And now, developers sense the advantage of tying it to Anthropic. 

“When you depend on a third-party runtime, you are always waiting for someone else to fix bugs or ship features,” Kolavi added, explaining how Anthropic now gains greater control. The acquisition will enable Anthropic to shape the developer experience around Claude Code and other products without friction. 

“They can tighten the integration, improve reliability and ship better defaults for people who build tools on top of their stack,” he further said. 

After Claude Code reached a $1 billion run-rate in six months, Anthropic said Bun represents “the kind of technical excellence we want to bring into Anthropic.”

It described Bun as “essential infrastructure for AI-led software engineering”, signalling that controlling the runtime is now part of Anthropic’s core strategy.

For Bun, the business reality had become increasingly complex to ignore. When asked about sustainability, its default answer had been that it would eventually build a vertically integrated cloud-hosting product. 

However, the company admitted this no longer made sense in an environment where AI coding tools are reshaping developer workflows. The infrastructure layer was becoming the centre of gravity, not the cloud product.

“Forcing ourselves down the prescribed path felt wrong when AI coding tools are getting this good, this fast,” the company said, explaining that joining Anthropic offered a more coherent long-term direction.

What Remains the Same

This isn’t an ‘aqui-hire’; the same team will continue working on Bun and will also expand its team. Bun will also continue to remain open source. 

However, the acquisition also invited ideological reactions. David Heinemeier Hansson, co-creator of Ruby on Rails, a server-side web application framework written in Ruby, called it “a beautiful act of corporate patronage”. 

Although he denied assigning a deep technical or strategic rationale behind the deal, he still welcomed it, arguing that it protected Bun from the pressure to impose a business model on open-source tooling simply to satisfy venture capital.

But one software developer questioned Hansson’s view, noting that “whenever open source switches hands, it starts to raise questions about whether it will stay that way in the long term.”

In response, Hansson stated, “There was zero chance it was going to ‘stay the way it was’ given their venture capital backing. VCs don’t do corporate patronage, but wealthy AI companies can.”

Beyond these concerns, contributor rights required clarity, even as Anthropic says Bun will remain open source. 

Jarred Sumner, CEO and co-founder of Oven, said in a Hacker News thread, “With Bun’s existing OSS license and contribution model, all contributors retain their copyright.”

“An acquisition of this kind cannot change the terms under which prior contributions were made without explicit agreement from all contributors,” he added, noting that any future Contributor License Agreement (CLA) would only apply to new submissions and would not retroactively alter ownership of existing code.

The Technical Rationale

In addition, one user on HackerNews pointed to a deeper technical context behind the acquisition. They stated that many people misunderstand the deal because they view Bun as just another Node.js-compatible runtime or bundler, akin to Deno or npm.

“But I think it’s a really smart move if you think of where Bun has been pushing into lately, which is a kind of cloud-native self-contained runtime,” they added. 

This is true. The runtime now ships with built-in S3 support, SQL clients, Redis, streaming features and the ability to compile full applications into portable single-file executables. 

Bun v1.2 added “a built-in PostgreSQL client and S3 client”, while v1.3 introduced “a Redis client, a MySQL client… and several improvements to bun install.”

“For an agent like Claude Code, this trajectory is really interesting, as you are creating a runtime where your agent can work inside of cloud services as fluently as it currently does with a local filesystem,” the user added. 

“Claude will be able to leverage these capabilities to extend its reach across the cloud and add more value in enterprise use cases.”

But the real value of the acquisition can be attributed towards the broader market trends.

The State of AI report, released by Andreessen Horowitz (a16z) and OpenRouter, stated that programming now accounts for more than half of all LLM token usage on OpenRouter, up sharply from about 11% at the start of the year.

Anthropic leads this category. Its models serve around 60% of programming-related traffic, compared with roughly 8% for OpenAI and about 15% for Google. 

Besides, coding prompts are expanding as well, often exceeding 20,000 tokens. Such workloads demand strict consistency in memory handling, startup performance, concurrency and execution semantics. Owning the runtime becomes part of maintaining reliability at scale.

Bun’s acquisition also aligns with the shift towards agent-driven workflows. The report shows that reasoning-heavy models now account for more than 50% of all LLM tokens, and that tool use—especially code execution—is rising.

A runtime optimised for agents becomes as crucial as improvements to model architecture.

More Such Acquisitions?

Historically, we’ve seen companies acquire open-source software. These include Microsoft acquiring GitHub, VMware acquiring SpringSource or GitHub acquiring Semmle. But what does Anthropic’s acquisition signal towards the broader industry trend in AI?

According to Kolavi, this certainly sets a precedent. “It shows AI companies are thinking beyond models and are willing to acquire core developer infrastructure. It gives them a direct path to influence how code is written, tested and deployed,” he said. 

He added that if this works out, we will probably see more deals in which AI teams buy the runtime, package manager or other low-level parts of the stack instead of building only on top of tools from the open ecosystem.

Besides acquiring frameworks and software stacks, acquiring the very team that built them could mean more. 

For instance, Kirk Kasier, a software developer and the author of Make Art With Python, described his thoughts on such deals to AIM, “I’d assume more of the value is in acquiring the team who is more familiar with optimising a runtime’s performance.” 

The post Why Anthropic Really Bought Bun appeared first on Analytics India Magazine.

Generated by RSStT. The copyright belongs to the original author.

Source