The convenience of playing a game in your browser without installing anything can't be beaten. It's perfect for a quick game where administrators restrict rights otherwise, like offices or universities, as well as for non-Windows operating systems.

There are now sites that leverage blockchain technology for faster multiplayer gaming, sites that let you save game progress, and even sites where you can find free downloadable games.

1. GameDatum (Web): Large Collection of Free Browser and PC Games

GameDatum is an aggregator of the best free-to-play games available online. Not only does it feature browser-based games, but it also includes several PC gaming titles for the Windows operating system, and of course, you'll need to download these games to play. But the good news is that you can then play them offline.

Not all the browser games on GameDatum are hosted on the website. For several popular games, like Settlers Online or Travian Legends, it only serves as a link to the host site. But you can still use GameDatum as a place to bookmark all these games by creating a "Playlist" after you register for an account.

Of course, the best part of GameDatum is game discovery. With hundreds of games in the catalog, you probably want to use the game filter menu to add or remove genres like MMO, MMORPG, shooter, strategy, MOBA, Battle Royale, card games, anime, racing, sports, social, fighting, indie, open world, sci-fi, simulation, action, and fantasy. Each game includes a short description, minimum system or browser requirements, and release date.

2. Saito Arcade (Web): Multiplayer Games in Browser on Blockchain Tech

Saito is a layer-1 blockchain project that allows blockchain applications to run directly through a web browser. To demonstrate its capabilities, they released Saito Arcade, a collection of browser games and emulators for retro gaming.

All of the games on Saito Arcade are multiplayer, and the site loads a community chat window to see who's active, invite others to play, and interact with online players. You'll see the list of games in the left sidebar and open games highlighted in the middle to join. You start with an anonymous account and a random name, but you can change that.

The games on Saito Arcade have several cool titles you wouldn't find in other places. For example, there are Settlers of Saitoa (a Catan clone) and Epidemic (a Pandemic clone). You can even play the classic arena shooter Quake 3 within the browser! And they have a Nintendo 64 emulator running through the browser to play classic retro arcade games in single-player mode, like Mario Kart 64 and Legend of Zelda: Ocarina of Time.

3. Simmer.io (Web): Play and Discover Unity WebGL Games by Indie Developers

Simmer is a site for indie game developers who build video games with the Unity platform to share them as browser games. The developer can just export it to the WebGL format and then drag-and-drop to Simmer to upload it. It's like a "YouTube for games," as the site boasts.

This ease of use for developers means that you get a lot of independently-made games on Simmer that you won't find elsewhere. You'll find the latest editor-recommended games as the first round-up of titles to play — the site is largely run by one person. Scroll down for other lists like the latest uploads, games from early Simmer adopters, and mobile-ready games built with Unity's Project Tiny.

It's a shame that Simmer doesn't let you browse titles by genre, as that's how most people prefer to discover new games. Still, it's hard to complain, given how well the games run in the browser and the sheer variety of new games added daily.

4. IO Games Space (Web): Massively Multiplayer and Fast Games in Browser

While there isn't a clear definition of IO games, we like GameNGuide's explanation: "browser-based, free-of-charge, multiplayer, and casual game with relatively poor graphics." From Agar.IO onwards, these "in/out" games have been the internet's favorite go-to when you want a quick gaming session in your browser, especially at work. But it's always been difficult to find them as they're all scattered across the web on their own website. IOGames.Space tries to list all of these great games in one place.

You can quickly check out the featured titles (most played on the site in the past week), newest added games, most popular games of all time, classic IO games, and more. You can also sort by genres like shooter, battle royale, free for all, team, zombies, space, tower defence, RPG and more, if you click the little blue arrow at the top-left corner. This sorting was sorely missing on a similar site Kevin Games, which we featured while talking about the best free browser game sites for multiplayer games.

Each game on IOGames.Space has a short description and sometimes includes a gameplay video to show what it's like. Registered users can choose their own nickname.

5. Crazy Games (Web): Huge Collection of HTML5 Games, With Progress Saving

After Adobe finally killed Flash in 2020, online games defaulted to HTML5. Crazy Games has collected one of the largest collections of these games in one place, with an easy-to-browse interface and a few features like saved games.

Currently, there are over 5,000 games in their catalog, spread across genres like 2-player, action, puzzle, multiplayer, platform, escape, tower defense, car/bike, shooting, and more. You can also quickly check featured games, new additions, and trending titles. Hovering over any game will show you a quick GIF animation of the gameplay, making your decision easier. If you're having trouble choosing, click the "random" button to start any game.

If you register for an account on Crazy Games, you unlock the ability to save game progress, which can be invaluable for some single-player games. You can also save your favorite games and view what you played recently. And as you play more, Crazy Games will start learning your preferences and recommend games.

Pro Tip: Use Your System Browser

No matter which site you use to play these games, you'll need a modern browser. Both Edge and Safari can support these and should be your preferred option. Other third-party browsers like Chrome, Firefox, or Vivaldi will place a higher load on your system memory and slow down the whole computer.