How do I unscramble a set of letters?

Type them into the finder in Letters I have mode. It returns every word that can be spelled from them, in any order, using no letter more often than you typed it - including the shorter words, which is usually where the playable answer is.

Do I have to use every letter?

No. Results include words that use only some of your letters, grouped by length with the longest first. That is what makes it useful for a Scrabble rack, where the seven-letter play is rarely available. If you do want the full-length answers only, set the length filter.

What about a blank tile or an unknown letter?

Type ? for each blank. A blank stands in for any letter the rack is short of, and because it scores nothing, any word that needs one is shown with its real score rather than its face value. If instead you know where the letters go, switch to Pattern mode: there ? means one unknown position and * means any run of them.

Which letters spell the most words?

AERST, with 15 ordinary English words: rates, tears, arets, aster, earst, reast, resat, sater, stare, stear, strae, tares, tarse, taser, teras. The table above lists the rest.

Unscramble Letters

Give it a jumble of letters and get back every word they spell. It works on anagrams, word-game racks, Jumble puzzles and anything else where you have the letters but not the order— and it runs in your browser, so nothing you type is sent anywhere.

Unscramble your letters

Type the letters below. Letters I have mode treats them as a bag of tiles: order does not matter, and every word that can be built from them comes back, longest first, with the everyday words ahead of the archaic ones. All 315,007 words are searched.

The letters that spell the most words

Some racks are far more productive than others. These are the 24 sets of five to seven letters that spell the most ordinary English words—every one of these is a full anagram, using all the letters given.

AERST 15rates, tears, arets, aster, earst, reast, resat, sater, stare, stear, strae, tares, tarse, taser, teras
AEPRS 14spare, apers, apres, asper, pares, parse, pears, prase, presa, rapes, reaps, repas, spaer, spear
AELST 12least, tales, steal, leats, salet, setal, slate, stale, stela, taels, teals, tesla
ACERS 11acres, races, acers, cares, carse, caser, escar, sacre, scare, scrae, serac
AELRST 11alerts, alters, artels, estral, laster, ratels, salter, slater, staler, stelar, talers
AEPRT 11apert, apter, parte, pater, peart, petar, prate, preta, repat, taper, trape
AELPS 10lapse, leaps, pales, peals, pelas, pleas, salep, sepal, spale, speal
DEILS 10slide, deils, delis, diels, eilds, idles, isled, sidle, sield, siled
DEORS 10deros, doers, dores, dorse, doser, redos, resod, rodes, rosed, sored
EERST 10trees, reset, ester, reest, seter, steer, stere, teers, teres, terse
EOPST 10estop, pesto, petos, poets, poset, poste, potes, stoep, stope, topes
ACEPRS 9capers, crapes, escarp, pacers, parsec, recaps, scrape, secpar, spacer
AEINRST 9anestri, antsier, nastier, ratines, retains, retinas, retsina, stainer, stearin
AELPST 9plates, palest, palets, pastel, petals, pleats, septal, staple, tepals
AELPT 9plate, leapt, lepta, palet, patel, pelta, petal, pleat, tepal
AELRS 9laser, arles, earls, laers, lares, lears, rales, reals, seral
AELSV 9slave, avels, laves, levas, salve, selva, vales, valse, veals
AEPST 9tapes, paste, pates, peats, pesta, septa, spate, speat, tepas
AIRST 9airts, artis, astir, raits, sitar, stair, stria, tarsi, tiars
EGINR 9niger, ering, grein, negri, nigre, reign, reing, renig, ringe
EINRST 9insert, estrin, inerts, inters, niters, nitres, sinter, triens, trines
EIPRS 9epris, peris, piers, pries, prise, ripes, speir, spier, spire
ELORS 9roles, eorls, lores, loser, orles, relos, resol, soler, sorel
IORST 9riots, roist, rosit, rosti, rotis, tiros, torsi, trios, trois

Anagrams, jumbles and racks are the same problem

An anagram uses all the letters and nothing else. A Jumble puzzle is the same thing with the answer guaranteed to exist. A Scrabble rack is looser: you may use some of your tiles rather than all of them, and a blank tile can stand in for one you do not have. The finder above handles all three, because it answers the general question—what can these letters spell?—and lets you narrow it with the length filter when you want the strict version.

The one case it deliberately treats differently is when you know where some letters go. That is a pattern, not a jumble, and it wants Pattern mode: C?T finds cat, cot and cut, while the same three characters as a rack would find every word spellable from a C, a T and one blank tile. Guessing which you meant would get one of them wrong every time, so the mode switch asks.

Questions

How do I unscramble a set of letters?: Type them into the finder in Letters I have mode. It returns every word that can be spelled from them, in any order, using no letter more often than you typed it—including the shorter words, which is usually where the playable answer is.
Do I have to use every letter?: No. Results include words that use only some of your letters, grouped by length with the longest first. That is what makes it useful for a Scrabble rack, where the seven-letter play is rarely available. If you do want the full-length answers only, set the length filter.
What about a blank tile or an unknown letter?: Type ? for each blank. A blank stands in for any letter the rack is short of, and because it scores nothing, any word that needs one is shown with its real score rather than its face value. If instead you know where the letters go, switch to Pattern mode: there ? means one unknown position and * means any run of them.
Which letters spell the most words?: AERST, with 15 ordinary English words: rates, tears, arets, aster, earst, reast, resat, sater, stare, stear, strae, tares, tarse, taser, teras. The table above lists the rest.