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What is a Mar file?

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  • 2 min read

The average PC user now uses more programs than ever before, meaning an even greater number of unique file extensions. While most commonly used files share common extensions and can be opened or accessed by a number of different programs, there’s still no shortage of unique file extensions that require a specific program. 

In this article, we’re talking about MAR files, what they are, what they do and what programs support them.

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MAR files explained

MAR files are application update files used by Mozilla programs including Firefox, Thunderbird and Seamonkey. These include new updates and enhancements for the respective program and are often included with Mozilla installation bundles. That said, Mozilla has made the format publicly available meaning third-party developers can also push their own updates using these files. 

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While Mozilla programs usually automatically download and install their updates using MAR files, generally deleting them after the process is complete, they can also be used to manually install updates without having to interface with the program. This can save IT and system administrators a lot of time when updating field deployments without having to individually go and update every program which can be a rather time-consuming process. 

MAR files contain code for the respective Mozilla program that they’re targeting, which means if you launch them by double-clicking the file it’ll automatically open the target program and update it to the latest version as dictated in the MAR file itself. Keep in mind that this method only works if your file associations are set up correctly. If they aren’t you’re going to have to launch the file in the target program manually.

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Yadullah Abidi

Yadullah Abidi

Yadullah is a Computer Science graduate who writes/edits/shoots/codes all things cybersecurity, gaming, and tech hardware. When he's not, he streams himself racing virtual cars. He's been writing and reporting on tech and cybersecurity with websites like Candid.Technology and MakeUseOf since 2018. You can contact him here: