> For the complete documentation index, see [llms.txt](https://docs.fluid.so/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fluid.so/browser-engines.md).

# Browser Engines

Fluid allows user to choose between multiple browser engines. There are currently two engines supported in Fluid.

* Chromium, which is used in many browsers such as Google Chrome, Microsoft Edge, Opera, Arc and many more.
* Gecko, which is used in Mozilla Firefox, and also acts as the base for Mozilla Thunderbird.

### Switching Engines Globally

To change the engine used for all new browser tabs and windows, go to the [Settings](/basics/settings.md), then General Settings and click on the browser engine you want. Be aware that this does not affect any window that is already open. If you want to switch all windows to the selected engine, either close and re-open all the windows, or restart Fluid.

{% hint style="info" %}
Cookies and logins are not synced between engines. If you switch the engine, you will have to log back into all websites.
{% endhint %}

<div align="center" data-full-width="false"><figure><img src="/files/YUAUfSGLO9X5fpJjspNu" alt=""><figcaption></figcaption></figure></div>

### Switching Engines Per Tab

To switch the browser engine per tab, click the three-dot menu at the top and select either "Chromium" or "Gecko." The current selection is highlighted with a white outline. Keep in mind that this option currently resets when you re-open Fluid.

<div align="center"><figure><img src="/files/fB6pzD08r0tCouqyHasd" alt="" width="312"><figcaption></figcaption></figure></div>


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