You can configure any of the following custom domain types:
docs.mydomain.commydomain.com/docsmydomain.comFern recommends using the Fern Dashboard to set up custom domains. The Dashboard automatically provides the correct DNS records based on your domain type. If you prefer to configure your domain manually, follow the instructions on this page.
Expand the section below that matches your domain type:
To host your documentation on a subdomain like docs.mydomain.com, you need to create a CNAME record in your DNS settings.
Update the domain in docs.yml
Add your custom-domain and merge your changes into main. Here’s an example.
Contact Fern via your dedicated Slack channel or email to receive:
Log in to your domain registrar’s dashboard and navigate to the DNS settings for your domain. Add the following records:
Replace docs with any subdomain you want to use.
If you are using Cloudflare, you should ensure the record isn’t proxied.
Once Fern has completed your setup, you’ll be able to access your documentation at docs.mydomain.com. SSL will be automatically provisioned for your domain, but it may take a few minutes to propagate globally.
This feature is available only for the Team and Enterprise plans. To get started, reach out to support@buildwithfern.com.
To host your documentation on a subpath like mydomain.com/docs, you need to edit your docs.yml configuration and set up a reverse proxy on your infrastructure.
Configure the url in docs.yml
Append that subpath to the end of the url. This example use docs for the subpath, but you can use any word you like, such as reference or developer.
A subpath can’t be routed with DNS alone — your infrastructure has to forward requests from mydomain.com/docs to Fern’s origin with the x-fern-host header set to your bare domain. Follow the reverse proxy setup instructions for your provider (Cloudflare Workers, AWS CloudFront, Netlify, Vercel, Nginx, Akamai, or Caddy).
Once Fern has completed your setup, you’ll be able to access your documentation at mydomain.com/docs. It may take a few minutes for DNS changes to propagate globally. Try accessing your new docs site from a mobile device or incognito browser to confirm everything is working.
If you see partial page loads or HTTP/2 transfer errors, nginx’s lack of native Brotli support may be the cause. Fern’s CDN serves Brotli-compressed responses by default, which nginx can’t decode when proxying upstream.
Add this directive to your nginx config to request only supported encodings:
To host your documentation on a root domain like mydomain.com, you need to edit your docs.yml configuration and configure DNS records.
Contact Fern via your dedicated Slack channel or email to receive:
You’ll need the following DNS records configured for your root domain.
This redirects mydomain.com to www.mydomain.com.
After you add these records, Fern will provision a SSL certificate.
Once Fern has completed your setup, you’ll be able to access your documentation at mydomain.com. SSL will be automatically provisioned for your domain, but it may take a few minutes to propagate globally.
To serve your documentation from multiple custom domains (e.g., for partner or white-label deployments), follow the above steps for each domain (subdomain, subpath, or root domain), then configure an array in your docs.yml:
After configuring multiple domains in your docs.yml, contact Fern via your dedicated Slack channel or email to complete the setup. You’ll receive DNS configuration details for each domain.