This online calculator can check if a word/phrase is an isogram. For those who curios what isogram is, here is some information from wikipedia:
An isogram (also known as a "nonpattern word") is a logological term for a word or phrase without a repeating letter. It is also used by some to mean a word or phrase in which each letter appears the same number of times, not necessarily just once.
Isograms can be useful as keys in ciphers, since isogram sequences of the same length make for simple one-to-one mapping between the symbols. Ten-letter isograms like PATHFINDER, DUMBWAITER, and BLACKHORSE are commonly used by salespeople of products where the retail price is typically negotiated, such as used cars, jewelry, or antiques. For example, using the PATHFINDER cipher, P represents 1, A represents 2 and so on. The price tag for an item selling for $1200 may also bear the cryptic letters FRR, written on the back or bottom of the tag. A salesman familiar with the PATHFINDER cipher will know that the original cost of the item was $500, so that if the price is negotiated he will not accidentally eliminate all of the 240% margin in the $1200 price shown to prospective buyers. A twelve-letter cipher can be used to indicate months of the year. Isograms are useful in the game of Hangman and could make a particularly difficult puzzle on the game show Wheel of Fortune.
The longest known English isogrammic word is "subdermatoglyphic" (17 letters). You can use the calculator below to check if the word or phrase is an isogram.