Seapilot Navigation App uses vectorized S-57 chart data from national maritime administrations. The chart presentation is based on professional standards for ECDIS (Electronic Chart Display and Information System).
Nautical charts are purchased directly in the Seapilot app. You purchase by country and the charts include the coastal areas and – for some countries – major lakes and waterways as well. Current price for each chart can be found directly in the app (Settings -> Charts). You can overlook your subscriptions on your account page. Some charts are free of charge (US charts for instance). Those might be stated as Purchased in your account settings – please note that it doesn’t mean that you’ve actually purchased and paid for them.