Cloudflare Acquires Deno: What It Means for JavaScript Runtimes

The "JavaScript runtime wars" concluded with the acquisition of Deno, a JavaScript runtime, by Cloudflare. This move is notable because Cloudflare already possesses its own runtime and deployment platform. The acquisition raises questions about Cloudflare's motivations and the future of Deno.

The Rise and Fall of Deno

In 2009, Ryan Dahl introduced Node.js, an open-source runtime that enabled JavaScript to run on servers. Nine years later, Dahl expressed regrets about Node.js in a talk titled "10 Things I Regret About Node." He then unveiled Deno, a new runtime built from scratch to address these regrets.

Deno distinguished itself from Node.js by including a built-in formatter, linter, and test runner. It supported TypeScript, prioritized security by default, and offered a streamlined approach to package management. Deno 1.0 launched in 2020.

By 2021, Dahl announced Deno Deploy, a serverless platform, and secured $5 million in seed funding. Deno gained significant traction, with Netlify and Supabase building their edge functions on it, and Slack utilizing it for its new app platform. In 2022, Deno received $21 million in Series A funding from Sequoia and launched Fresh, a web framework, suggesting a promising future in server-side JavaScript.

However, Deno's momentum waned. Node.js, in the interim, incorporated features like fetch, a permission model, and direct TypeScript execution, eroding Deno's competitive edge. Concurrently, Deno's revenue-generating products struggled to gain sufficient traction. Deno Deploy scaled back from 35 regions to six, Deno KV remained in beta after its 2023 launch, and Fresh experienced infrequent releases.

During this period, Ryan Dahl also engaged in a legal battle with Oracle over the JavaScript trademark, a cause that, while noble, was not aligned with investor expectations. The declining sentiment led to a blog post by developer David Bushell, who argued that Deno was effectively "dead," constantly playing catch-up with Node.js through compatibility fixes. Dahl himself eventually reached a similar conclusion.

Cloudflare's Acquisition and the Future of Deno

Recognizing the challenges, the Deno team shifted its focus to problems beyond the runtime, such as distributed computing, state coordination, and scaling. Their research led them to Cloudflare's Durable Objects, which are essentially small, single-threaded servers with private SQLite databases and WebSocket capabilities.

The limitation of Durable Objects was their exclusivity to Cloudflare's platform. In response, the Deno team developed Cell D, their own version that allowed Durable Objects to run on self-hosted servers at a lower cost. Surprisingly, Cloudflare welcomed this development. The creator of Cloudflare Workers acknowledged that while Cloudflare had been accused of vendor lock-in, their Workers runtime had been open-source since 2022, and they had long desired a self-hostable version but hadn't managed to build one.

Upon the Deno team's success with Cell D, Cloudflare, with its substantial market capitalization, acquired the company. The plan is for Ryan Dahl and co-founder Bert Belder to integrate Cell D into Cloudflare's open-source Workers runtime, enabling anyone to run Workers and Durable Objects on their own servers with official Cloudflare support.

A significant focus for this integration is AI agents, as Durable Objects are well-suited for agents requiring affordable compute, persistent state, and real-time connections.

However, the acquisition has negative implications for existing Deno users. Cloudflare will only provide bug fixes and security patches for Deno for the next year, after which development will cease. Users of Deno Deploy have approximately six months to migrate their applications.

This acquisition, following Anthropic's acquisition of Bun and Cloudflare's earlier purchase of V, leaves Node.js as the only major JavaScript runtime not owned by a cloud provider.

JetBrains and Juny Light

For Deno developers needing to migrate, JetBrains offers a solution. Every JetBrains account now includes a free baseline AI model called Juny Light, which operates within the IDE and CLI. Juny Light assists with tasks like renaming functions and scaffolding tests without incurring costs. While more complex work might necessitate a Frontier model, Juny Light integrates with JetBrains AI, allowing for parallel agent execution and review of changes before implementation.