Key point
One final check
A live URL is not enough. Your project should open cleanly from a custom domain if you use one, and it must work on a phone.
Recruiters and judges may open your link on mobile data between meetings. Make the first screen load, fit, and explain the project fast.
Domain basics
A custom domain is optional for many hackathon submissions, but it looks cleaner than a long platform URL. You can use your host URL if you do not own a domain.
If you use a domain, connect it from your hosting dashboard first. Then update DNS records in your domain provider. DNS changes can take time, so do this before the deadline day.