Cloudflare buys Deno, and Node.js creator Ryan Dahl moves his team to Workers

The joint post by Dahl and Cloudflare engineer Kenton Varda went up on October 9. Dahl wrote a companion post on the Deno blog the same day. Neither post mentions a price.

The Register calls it an acquihire. That's when a company buys a startup mostly to hire its people.

• The people: Dahl and 12 of his Deno colleagues, according to The Register.
• The leaders: Dahl and Deno engineer Bert Belder will run the new project.
• The project: celld, an open source tool the Deno team released in August.
• The mission: merge celld into workerd, Cloudflare's own open source runtime, so Workers apps can run anywhere.

Why it matters: Cloudflare isn't buying Deno to grow Deno. It's buying the team that already built the piece Cloudflare says it never found time to build itself.

If you've built a website in the last 15 years, you've probably touched his work. Dahl introduced Node.js in 2009, in a Berlin warehouse, with a 500-line chat server demo.

Node let developers run JavaScript on the server, not just in the browser. It used Google's V8 engine and handled thousands of requests with much less memory than the Apache servers of the time, The Register notes.

• 2009: Node.js debuts.
• 2018: Dahl shows Deno, a rewrite that fixes what he felt Node got wrong. The name is an anagram of "Node."
• 2022: Sequoia backs Deno with $21 million, The Register reports.
• August 2026: Deno reaches about 400,000 monthly users, and the team releases celld.
• October 2026: the team joins Cloudflare.

Deno added built-in web requests, a permission model and native TypeScript support. It was a cleaner design. But developers kept asking for Node compatibility.

"What we found over years of working on Deno is that you can't really deviate from Node.js very much," Dahl told The Register.

He said the team had to backpedal on some of its original promises over time. Deno ended up as, in his words, a kind of alternative Node.js implementation.

Here's the part that matters most if you build on Deno today. The Deno blog spells it out.

The runtime stays open source under the MIT license. Deno says it welcomes anyone who wants to keep developing it, and The Register reports Dahl is looking for a new home for the project.

Paying Deno Deploy customers will get help moving their apps to Cloudflare Workers.

In real life If your side project runs on Deno Deploy, put a reminder in your calendar for about four months from now. That leaves time to move it to Workers, or another host, before the six months run out.

First, a little background. Cloudflare Workers runs your code on Cloudflare's network, close to your users, instead of on one big server. Durable Objects is a Workers feature where each object is like a small server with its own SQLite database.

Dahl calls it a distributed singleton. Think of a chat app: one Durable Object per channel. Each channel keeps its own messages and connections, so the app spreads across machines without extra plumbing.

It's like giving every group chat its own tiny office, with its own filing cabinet, instead of cramming everyone into one huge room.

The catch: this only really worked on Cloudflare's own network. Cloudflare open-sourced the Workers runtime as workerd in 2022, but Varda admits its Durable Objects support is limited to a single instance. Good for testing, not for scale.

celld fills that gap. It's a single program written in Rust that runs Workers and Durable Objects across many machines, with object storage as its only outside dependency.

To run it, you start many copies of celld and point them at one storage bucket. celld handles where each object lives, how requests find it and how its data is saved. Dahl says running Deno Deploy taught him the opposite lesson: multiple clouds, multiple databases and tangled services.

Varda explains why Cloudflare never built this itself. Its own production system for routing Durable Objects is huge, built for hundreds of locations and run by a team of reliability engineers. Not something you'd want in your own data center.

Varda writes that celld was what Cloudflare had wanted to build for a while, "and Deno Land was building it for us!"

That's a common claim online, and Varda takes it on directly. The theory goes that apps written for Workers are hard to move, so customers end up trapped.

Under that theory, celld should scare Cloudflare. It lets Workers apps move to other providers. Instead, Varda says the company was delighted when it came out.

• Why Workers is different: Varda says the design simply makes it cheap and easy to run an app in hundreds of places at once.
• Why open source helps: when Cloudflare pitched Workers for Platforms to customers like Shopify in 2022, he says they needed the runtime to be open source before they would sign.
• The honest part: he writes that some former customers did leave using workerd, and that this is fine.

Varda also admits that few people run workerd in production, and that most don't know it's possible. Cloudflare, he writes, didn't build enough tools and services around it, and the Deno team knows how to make a self-hosted runtime pleasant to use.

Cloudflare's aim now is to make self-hosted workerd a first-class, supported way to run Workers apps. Varda promises more announcements in the coming months.

Both Dahl and The Register point to AI. Dahl writes that Durable Objects combine things agent harnesses need: cheap serverless execution, saved state, live WebSocket connections and a simple JavaScript interface.

By the numbers: The Register writes that a runtime like this could need about 300 KB of memory per instance. That compares with the hundreds of megabytes Node or Deno need today, a big saving for anyone running lots of small agents.

Dahl is blunt about where he thinks servers are heading.

"I am now of the opinion that if you're choosing Node.js for building servers, you're doing it wrong," Dahl told The Register.

He told the outlet that most servers today operate at the Linux virtual machine layer, and that Cloudflare Workers don't. The Register also notes that independent JavaScript runtimes are thinning out, after Anthropic's recent purchase of Bun.

If you want more on Cloudflare's recent moves, we covered its Basin data platform and its open-weight Clef models.

• If you deploy on Deno Deploy: you have six months. Start planning a move now, and check Deno's migration help if you pay for the service.
• If you use the Deno runtime: nothing breaks today. You get a year of fixes, and the code stays open source for anyone to continue.
• If you publish to JSR: it keeps running, now on Cloudflare's infrastructure.
• If you're curious about Workers: you can already try self-hosting celld or workerd, and running Workers on your own servers should get easier.