Which Word app for iPhone and iPad

Stuck on a crossword puzzle or arrow words?
Want to impress your friends mastering hangman, scrabble, boggle or Wordfeud?

The app What Word is the perfect companion for your word games and allows you to:
Function 1 - Help for crossword / arrow words / hangman - Find existing words from a word for which there are some missing letters.
Function 2 - Help for scrabble / boggle / Wordfeud / anagrams - Get the list of words achievable with a given stack of letters (anagrams), with a sorting in alphabetical order or by number of points, according to the rules of scrabble.
Function 3 - Help for scrabble / wordfeud - Get the list of words achievable with a given stack of letters + a letter from the board.
Function 4 - Online dictionaries - Access definitions of words in one click, without leaving the application.

The full version gives you bonus access to:
Advantage 1 - The search function of words with missing letters for words of 7 letters or more.
Advantage 2 - The search function of words formed from a given stack, without restriction.