Web site to show GPX with elevation?

I notice that a GPX file contains not only lat + lon but also elevations:

  <trk>
    <name>Some route</name>
    <trkseg>
      <trkpt lat="50.64536" lon="3.05657">
        <ele>23.6</ele>
      </trkpt>
…
      <trkpt lat="50.63836" lon="3.06491">
        <ele>32.7</ele>
      </trkpt>
    </trkseg>
  </trk>

I was wondering if someone knew of a web site where I could simply upload a GPX file and have it drawn on a map with the route colored differently based on the elevation, ie. where the flat parts are drawn in green while the steep parts are shown in red?

Thank you.