Skip to main content
Your sandbox, just like any virtual machine, can expose ports. These ports let you connect to a process or app running in the sandbox.

​
Reserved ports

The following ports are reserved by Blaxel’s system:
  • 443: This port hosts the main sandbox API and is exposed via HTTPS
  • 80: Reserved for system operations
  • 8080: Reserved for sandbox API functionality
You can expose and use any other port on your sandbox.

​
Expose a port

To whitelist sandbox traffic in your network, you can retrieve the public IP addresses used by Blaxel.
You can expose specific non-reserved ports when creating a new sandbox by using the ports parameter. This allows you to access these ports from outside the sandbox, typically to create a preview URL on them. 
import { SandboxInstance } from "@blaxel/core";

// Create a new sandbox
const sandbox = await SandboxInstance.create({
  name: "my-sandbox",
  image: "blaxel/base-image:latest",
  memory: 4096,
  ports: [{ target: 3000 }]
});

​
Access the sandbox on a specific port

​
Via the sandbox API

This option requires your request to be authenticated. You can access your sandbox on a specific port through the sandbox API using the following URL format: 
https://sbx-{resource_name}-{workspace_id}.{region_id}.bl.run/port/{port_number}
For example to connect to port 3000 on my-sandbox in workspace abc123: https://sbx-my-sandbox-abc123.us-pdx-1.bl.run/port/3000

​
Via a preview URL

Preview URLs provide a simple URL that maps to an internal port of your sandbox. You can either make this URL fully public or secure it with token-based authentication. Generally speaking:
  • for file and process management in your sandbox, use the sandbox API or SDK.
  • to access running applications within the sandbox (such as a NextJS preview server on port 3000), use a preview URL instead.

Create preview URLs

Expose applications running within the sandbox via a direct preview URL.