Online play

There are many opportunities to play Scrabble online with players from around the world or against the computer. Some of these have tournaments set up. There is often a choice of lexicons, but we would like to have Collins Scrabble Words to match what we play at clubs and tournaments.
On web based platforms you can sometimes watch live games or view archived games.
On programs such as Quackle there is also deep analysis via simulations. Expert players use such programs to do post mortems.
Woogles is a web resource for competitive, real-time games. You need to register.
You can play against an AI bot (several types are available), against a friend or a stranger.

You can observe games in progress or examine a completed game.
The 2021 WESPA World Championship, an elite invitational event, was conducted online using Woogles. Other online tournaments are held using Woogles.
Scrabble Go
Scrabble Go This is the Scrabble app commissioned by Mattel and is available for Android and iPhone mobile devices. The app unfortunately displays advertisements and nags you to buy in-app purchases. It uses so-called free challenge, where if you play a disallowed word, the computer tells you and you get to have another go.
PlayScrab offers games with your friends, friendly games with strangers, or hotly fought league matches Choose from a variety of game lengths: finish a game in as little as ten minutes or take as long as three weeks Try it out by playing ten friendly games then subscribe for 5 GBP per year.
CSW19 is the Internet Scrabble Club which has been going since 2002. The website design is very simple and minimalistic, offering a retro feel with simple characters and colors. You can play against an opponent (worldwide or an AI bot) or observe a game in progess. Several game options include time limits per game. It is free to use (although paid subscribers get benefits) and is ad-free. The way that ISC works is explained here
David Webb, one of Britain's top players, has a YouTube channel zapateo99 which has videos of games he has played on ISC, with a voiceover explaining his thinking.
Quackle is a free artificial intelligence and analysis tool that rivals the best players in the world. It is available for Windows and Mac OS X and Linux. Here is how Kenji Matsumoto describes Quackle:
Quackle was created by two extremely strong Scrabble players: Jason Katz-Brown and John O’Laughlin. Quackle uses Monte Carlo simulation based primarily on points earned and letters left on the rack to make decisions, and allows you to input any position and then simulate, providing an analysis of which play is best as well as key statistics, such as bingo percentage, average score, and standard deviation.
Elise is another free artificial intelligence and analysis tool similar to Quackle. It is available for Windows. Elise is state-of-the-art crossword puzzle game analysis software with a design philosophy inspired by modern chess engines. It is a useful tool for serious players of Scrabble®. Elise plays a sharp game that will rival the best human players. Moves can be generated instantly using the "quick move find", or Elise can ponder moves deeply in simulation. Most simulations are done quickly, but long simulations can be interrupted at any time.
Elise uses exhaustive search to play a perfect end-game.
It has not been updated since 2013. You need to provide a lexicon (it has CSW12) .

Word study and judging

There are programs that can be used for searching for anagrams or patterns, for word study, and for adjudication of a play of one or more words. The strictest mode of judging is used in proper competitive play where a play of more than one word will only give a Yes or No, without revealing which words are wrong, and not giving extra information such as definitions or parts of speech.
CSW19, CSW21
Zyzzyva was originally written by Michael Thelen but is is now maintained by NASPA (the North American Scrabble Association) helps you study words and practice your anagramming skills. You can search for words, anagrams, and definitions, as well as give yourself cardbox quizzes. Zyzzyva is also useful for learning words for word games. This program has a full screen Word Judge mode, which can be useful for determining the validity of words while playing word games. It is available on Windows, macOS and Linux.
There are also mobile apps for iOs and Android
The Zyzzyva Word Judge is the de facto standard for adjudicating attournaments in Australia and indeed the world.
Ulu , available as an iOS app, is a word-lookup and tournament adjudication tool useful for a variety of word games, including Scrabble®, Words With Friends©, and crossword puzzles.
ULU comes equipped with both of the lexicons used in English-language Scrabble: the NWL2018 lexicon for North America, and the CSW2019 lexicon for the rest of the world.
ULU's Search page enables you to find words that match letter combinations, with or without blanks and wildcards. It also finds words matching any pattern you name, words that contain only a subset of letters you name, words of a certain length, or any combination of these things at once. You can also limit search results to show only the number of matches or to show which blanks make matches. Tapping a word brings up a page of more detailed information about that word.
ULU's Judge page lets you see whether or not words you type are all valid, as you would need when playing tournament Scrabble.
ULU also includes a customizable timer for use in tournament Scrabble or in other games

Other word games

Aerolith is a web app written by César Del Solar. Its main program is WordWalls where 50 scrambled words are shown and you try to solve them as quickly as possible. You must register to play.
Wordle became very popular at the start of 2022. It poses one puzzle per day, a mystery five letter word which you try to find with six or fewer guesses. Wordle bragEach guess elicits a response where each letter in your guess is displayed as green if it is correct and in the correct position, yellow if the letter is correct but in the wrong position and grey if it is not in the target word at all. The word may contain repeated letters. Your guess must be a real word (in its lexicon of over 10 000 words). The target word is chosen from a smaller lexicon of about 2500 more common words.
It became popular because you can boast on social media how many turns you took.
There are variants such as
Bee is a free web based version of the addictive daily competition in the New York Times (the New York Times puzzle is only available to paying subscribers ). There is a daily puzzle, but you can also try ones from earlier as well.
The goal of the puzzle is to find all of the words that can be created with the given seven letters. Words must be 4 letters or longer. Words must contain the middle letter. Letters can be used more than once.
Unforunately many words that you try are not in their lexicon. The E C D H I K W puzzle shown has 49 solutions in their system including what they misleadingly call a pangram (just one in this instance). They, and the New York Times, use pangram to mean a solution which uses all seven letters (perhaps with repeated letters).