Accessing Boxes and Ports

When Codio creates a new project, it will generate a unique subdomain name


where word1 and word2 are randomly generated words resulting in a unique domain name.

It is strongly recommended that you reference a Codio box running on a specific port using


If your PC is behind a firewall, access to external ports are often restricted. Using the recommended approach, the request will be made over port 80 and so will not be blocked by the firewall.

This approach allows both HTTP and HTTPS access over the full range of ports, 1024 to 9999.

Standard port addressing

You can also reference a Codio box using word1-word2-<port> This approach will work but be aware:

  • Port ranges are restricted to 1024 to 9499 for HTTP access
  • Port ranges are restricted to 9500 to 9999 for HTTPS access
  • If the PC you are working on is behind a firewall and it blocks access over non-standard ports, it will fail if it references a box using
  • You may waste your time and potentially your sysadmin’s time trying to diagnose why your browser will not talk to the Codio box.

Original Request Header

Should you need it, the X_FORWARDED_PROTO header contains original request schema.

Preview Menu

Codio offers a fully customizable Preview menu so you can preview both static files (.html) and server side files (.php files, Ruby and Node apps etc.) with a single click.

This feature lets you set up any number of ‘aliases’ both for static files and Box cli commands.