back to archive
1 min read

How Durable Objects work

celld brings the Durable Objects model to compatible infrastructure beyond Cloudflare. Two short videos explain the model and the runtime beneath it.

Ryan Dahl released celld. It brings Workers and Durable Objects to compatible infrastructure beyond Cloudflare, making the model useful in custom systems and easier to adopt without fear of vendor lock-in.

A Durable Object starts with a simple boundary: one named entity, its state, and the decisions that change it. The process serving the object can disappear; the object remains.

What does that change when designing a system? Start with this boundary and follow it far enough to see where it helps—and where it should end.

Durable Objects, explained

Keeping the promise

The runtime has a harder job: preserve that abstraction across replaceable processes and machines. celld is one answer. Follow a Durable Object through a failure and see how it continues elsewhere.

Durable Objects, under the hood

GPT-5.6 made both videos as animated Remotion slide shows under my direction.

Writing Practice explores the same boundary for agentic work: one Durable Object for each long-lived writing task.