Wordle solver

Type the word you guessed and press Add guess. Its five tiles appear in grey. Tap each tile until it shows the colour the game gave it: once for yellow, twice for green. Do the same for every guess so far, up to six. The list of words that fit, and the suggestions, change as you go.

Press a suggested word to add it as your next guess, then colour it in once the game has scored it. A letter that was green in the same place in an earlier row starts green, since it can't be anything else. If no word fits, the page names the row where the words ran out: usually one tile there is the wrong colour.

A word is kept only if guessing it against each of your guesses would give exactly the colours you tapped. That handles repeated letters the way the game does. Greens are given first; then each other letter turns yellow only while the answer still has an unmatched copy of it, left to right; anything left is grey. So if you guess GEESE and the answer is THOSE, the last two letters are green and the first two Es are grey, because THOSE has only one E and the green has used it.

This is why a grey letter doesn't always mean the letter is missing. Guess LLAMA against HELLO and the two Ls are yellow, but the A is grey; guess a word with three Ls and the third would be grey even though L is in the answer. Checking whole words, rather than a letter at a time, gets these cases right.

Each possible guess would split the remaining words into groups by the colours it would get. A good guess makes many small groups, so that whatever colours come back, few words are left. The score in bits measures this: the average information the colours would give. One bit halves the list; with 6 bits, about 64 words would be cut to about one.

Sometimes the best guess is a word that can't be the answer, marked so in the list, because it tests five new letters at once. Late in a game it's often better to play a word that could win. With hundreds of words left, only the candidates with the commonest letters are tried as guesses, to keep it quick on a phone; with fewer, every five-letter word in the list is tried. On this list the best opening guess is TARES, at 6.23 bits.