`fastn` can be used for creating dynamic websites. By default `fastn` maps the URL's path to file system to decide which `ftd` document to serve. This behaviour can be changed as described in [custom URLs guide](/custom-urls/). In this guide we will see how we can map any URL matching a given pattern to a `ftd` document. Dynamic URLs are specified in `FASTN.ftd` file under the `fastn.dynamic-urls` section:

-- fastn.dynamic-urls:

# User Profile Page
url: /<string:username>/
document: profile.ftd

-- import: fastn/processors as pr

-- record r-data:
string username:

-- r-data data:
$processor$: pr.request-data

-- ds.markdown: $data.message