How to link two domains using an HTTP header

HTTP requests and responses can contain a number of extra headers, which you can use to send along extra metadata about the server serving the request.

Carbon.txt supports using the CarbonTxt-Location header, to point to a carbon.txt served on another domain, In our case usually a managed hosting provider.

1. Follow the steps above to create your carbon.txt file

   Follow Steps 1 to 3 of the Getting Started guide above to create a carbon.txt file for your organisation.

2. Set the header on HTTP responses from the domain you want to show as green

   For example: my-org.com also owns me.my-org.com. In order to link me.my-org.com to the main carbon.txt file, when a request comes in for me.my-org.com, you would configure the server serving the request to add the following header.

   CarbonTxt-Location: https://my-org.com/carbon.txt

   We maintain a set of server config setup examples folder on github, for popular open source servers like Nginx, Caddy, Apache, and so on (pull requests gratefully accepted).