Agar.io Merge Timer is a free Agar.io modification to improve the game. It offers multiple features:

You can set the duration of the merge timer, making it easy to decide when to split, or to stay with one cell if your situation is dire.

A split button is provided, which makes the process of splitting a cell with the same cellmates easier and quicker. The split button is located in the bottom-right corner of the screen, and the timer will display when it is pressed.

A shortcut to the settings screen is provided, which allows you to save a nickname and checkbox settings for each cell.

When the settings have been saved, you can open the settings screen anytime you wish.