Configure Custom Domains

Custom domains give your environment a memorable, stable URL that persists across deployments. Instead of using a deployment-specific URL that changes with each deploy, a custom domain always points to the environment's current deployment.

How Custom Domains Work

• Custom domains are subdomains of .phemeral.app (e.g. my-api-production.phemeral.app).
• A custom domain is assigned to an environment, not a specific deployment.
• Traffic to a custom domain is routed to whichever deployment is currently active on the environment.
• When a new deployment is set as current, the custom domain automatically begins routing to it.

Add a Custom Domain

1. Navigate to your project in the dashboard.
2. Open the environment you want to assign a domain to.
3. In the Domains section, enter the subdomain you want (the .phemeral.app suffix is added automatically).
4. Submit the request.

If the subdomain is available, it is assigned to your environment immediately.

If the subdomain is already taken by another environment, choose a different subdomain and try again.

Remove a Custom Domain

1. Open the environment in the dashboard.
2. In the Domains section, find the domain you want to remove.
3. Delete the domain.

Traffic to the removed domain will no longer be routed to your environment.

Multiple Domains

An environment can have multiple custom domains. All of them route to the same current deployment.

Domain Format

Custom domains follow the format {subdomain}.phemeral.app.

Deployment Domains vs. Environment Domains

Deployment domains are auto-generated and immutable. They are useful for previewing or testing a specific deployment. Environment domains (custom domains) follow the current deployment as it changes.