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Cloudflare announced Worker Previews on September 22, 2026, introducing production-like test environments for individual Git branches. Available now, the feature gives each preview separate code, configuration, state, observability and a stable URL, allowing developers and coding agents to evaluate changes without sending them to production or a shared staging deployment.
One Environment per Branch
Developers can create an environment with `npx wrangler preview`; Workers connected to Git through Workers Builds can generate one automatically when code is pushed. Subsequent pushes update the branch's existing preview URL, which can be used for API requests, browser-based UI testing or automated checks. Multiple previews can run concurrently under the same Worker and appear alongside production in Cloudflare's dashboard.
Teams can define a shared preview configuration in Wrangler and then override settings for a specific branch. Custom domains are supported for testing behavior involving cookies, CORS, authentication providers and OAuth redirects. Cloudflare Access can restrict those preview addresses to signed-in visitors.
State and Diagnostics Stay Isolated
Each preview receives its own Durable Object namespace and Container application. This keeps sessions, storage, migrations and other stateful changes away from production and from parallel branch tests. Cloudflare says the same isolation also applies to logs, errors, metrics and traces, enabling developers to inspect a request's runtime activity without mixing signals from other environments.
The setup is designed for both manual review and agent-driven testing. An agent can open the preview in a browser, exercise a workflow, inspect Workers Observability data, modify the code and redeploy. Browser Run adds session capture, Live View and an option for a human reviewer to intervene when automation requires judgment.
Important Gaps Remain
Worker Previews do not yet isolate every part of a multi-service application. A service binding from a preview still reaches the bound Worker's production deployment. Previews may send Queue messages but cannot run Queue consumers, while isolated Workflow execution requires separate configuration. Cloudflare also says long-lived environments for staging, QA and per-developer use are planned rather than currently supported end to end.
The feature differs from Cloudflare's existing Version URLs, which point to a particular uploaded Worker version but do not create a branch-specific environment and can reference only production resources.
Source: Introducing Worker Previews: isolated preview environments for every change your agent makes
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