How Unscrambling Works
The obvious approach — generate every permutation of your letters and check each one — is unusable. Seven letters produce 5,040 arrangements; ten produce 3.6 million; twelve produce 479 million. Permutation counts grow as factorials, so that method collapses almost immediately.
The workable method inverts the problem. Instead of building candidates and testing them, we count how many of each letter you supplied, then walk the dictionary once and ask a much cheaper question of each word: can it be spelled from what you have? A word qualifies when every letter it needs appears in your set at least as many times as the word uses it.
The test
This turns a factorial problem into a linear one. The work scales with the size of the dictionary rather than with the number of letters you type, which is why adding a fifteenth letter does not slow the search down.
Which Letters Are Worth Holding
In word games the highest-scoring tile and the most useful tile are rarely the same. Q and Z score ten points each but combine with almost nothing, and a rack overloaded with them tends to stall.
The vowel balance
Around three vowels to four consonants is the working ideal on a seven-tile rack. Too few vowels and nothing combines; too many and you are left with words nobody can build on.
S is worth more than its face value
One point, but it pluralises a word already on the board and opens parallel plays. Strong players routinely hold an S back rather than spend it on a small score.
Common endings unlock long words
−ING, −ERS, −IEST and −TION account for a large share of seven and eight letter finds. Scanning the results for those suffixes first is faster than reading the whole list.
About the Word List
We search an open English word list of roughly 370,000 entries. It is deliberately broad, which means it includes inflected forms and uncommon words that a tournament dictionary might exclude.
That matters if you are playing competitively. Official play uses a specific reference — TWL in North America, Collins elsewhere — and the two disagree on thousands of words. A result here is a valid English word, but check your game’s own dictionary before challenging, or being challenged on, an unusual one.