This tool lists out all the arrangements possible using letters of a word under various conditions. This can be used to verify answers of the questions related to calculation of the number of arrangements using letters of a word.
This tool programmatically generates all the arrangements possible. If you want to find out the number of arrangements mathematically, use Permutations Calculator
For example, consider the following question.
How many words with or without meaning can be formed using the letters of 'CRICKET' such that all the vowels must come together?
The answer of the above problem is $720$. Using this tool, it is possible to generate all these $720$ arrangements programmatically.
At the same time, Permutations Calculator can be used for a mathematical solution to this problem as provided below.