Service name

Readme.io (https://readme.io/)

Proof

The subdomains reside on *.readme.io. It is a classic virtual hosting scenario like in other similar services.

To verify whether subdomain takeover may be possible, run:

http -b GET http://{DOMAIN NAME} | grep -F -q "Project doesnt exist... yet!" && echo "Subdomain takeover may be possible" || echo "Subdomain takeover is not possible"

(Assuming you have Readme.io account created.)

1. Go to dashboard.
2. Set Project Name and its subdomain. Subdomain does not need to match the domain you are trying to takeover.
3. In left sidebar, go to General Settings -> Custom Domain.
4. Set Custom domain to the domain you want to takeover.
5. Click Save.

Documentation

https://readme.readme.io/docs/setting-up-custom-domain