Since Agar.io is available as a browser game, its client side programming has been done using JavaScript. JavaScript is a programming language and the dominant programming language on the web. Modern browsers have an integrated engine that can run JavaScript code.

It is possible to add custom JavaScript code to any website with the help of an extension for the browser. This actually means it is possible to change the programming of Agar. Notice that this only includes the client side programming, not the Server’s programming. Therefore this cannot be used for classical cheating since critical things are calculated on the server, not on the client. For instance it would be possible to display ”1000000” as the value of the mass of your cell, but it is not possible to actually change the mass on the server.

However, custom scripts may improve usability, show hidden information or add additional features to the game.

To include custom scripts you have to install either the Greasemonkey (Firefox) or Tampermonkey (Chrome, Microsoft Edge, Safari, Opera, and Firefox) browser extensions. Once you have done that, find a custom script for Agar and install it. Some scripts might be outdated though and may not work as expected.

Warning: Custom scripts can contain malicious code!

Types[edit | edit source]

Scripts can be categorized in one of these three types:

  • Feature script: Focuses on adding or changing one or a very few number of features
  • Mod: Affects many aspects of the game. Example: Agar Tool
  • Total conversation: Changes the look of the game as well, especially of the user interface. Example: Legends Mod

Examples[edit | edit source]

  • Instead of pressing w multiple times to send mass, there are scripts that allow a player to press and hold the key
  • Instead of manually placing the mouse pointer in the middle of your cell to stop it from moving, just press a key
  • Display the size of viruses as a number overlaying the virus
  • Add support for chat to the game
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