Analyses your iTunes library and allows you to export your playlists either to text files of various formats (CSV, M3U, extended M3U, PLS. WPL and Excel XML) or - and that's the main thing - directly to your Spotify account. If a track cannot be mapped or found on Spotify, you're able to search and map manually.
Featuring lots of options for both types of export.
To try before you buy, have a look at the trial version here:
https://www.microsoft.com/en-us/p/mytunesplaylistexporter-trial/9n7f8n9wmr5f
(search the store for "myTunesPlaylistExporter Trial")
Of you own the trial version, you'll get a discount when buying the full version.