penna.io was a simple and lightweight blog and website builder all on a single static site.
By cleverly using a wildcard domain, the static site would adapt using the subdomain to a users setup.

For Example: hew.penna.io would load my site, while you.penna.io would load yours.
They are both the same static app underneath. Basically, it was making a website builder that functions more like the profile section of a normal app.

Users could log on, choose a subdomain, and start adding posts and content to have their own site. They could also link a real domain if they wanted.

The main use it was designed for was as a portfolio or as a blog. You would create “groups”, and each group would have a set of “items” - which had an editor for writing.