Is it possible to change the subdomain on a free Firebase app?

Any user (account) on Firebase can have up to 10 apps on a free/developer plan. Each app has a unique name and comes with database/authentication (available on https://<app-name>.firebaseio.com) and hosting (available onhttps://<app-name>.firebaseapp.com).

When you create a Firebase account an initial app is created for you, with a name in the format glorious-firename-1234. So with that app you'd have https://glorious-firename-1234.firebaseio.com and https://glorious-firename-1234.firebaseapp.com.

But you can also create your own app with a more memorable name, such as lazytotoro. This would lead to https://lazytotoro.firebaseio.com and https://lazytotoro.firebaseapp.com. This is available for free apps.

You only need a paid app, if you'd want to switch to https://www.lazytotoro.com or something like that.

Once a project is created, you can't edit its project-id. The project-id is the default site name of hosting. To get different site name:

1. You can set another name than that of provided by firebase console at project creation time. So, you can edit the suggested project name, for eg, example-name-123.firebaseio.com to like my-web-app.firebaseio.com

2. One project can have multiple sites. Go to https://console.firebase.google.com/project//hosting/main and click Add Another Site. You can give a new name to your new site (even if you can't edit name of existing!) You can read here for more

Now, Firebase launched web.app domains for all of the sites hosted on Firebase Hosting your site can also be accessed via my-web-app.web.app in addition to my-web-app.firebaseio.com