ALG File

What are ALG files and how to open them

Are you having problems opening an ALG file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your ALG files.

What is an ALG file?

An .ALG file is an AlgoBox Algorithm file.

AlgoBox Algorithm stores algorithms created by the French educational software AlgoBox, developed by Pascal Brachet. It is used for designing, testing, and executing mathematical algorithms in a school setting. The typical audience is secondary-level students learning algorithmic logic using structures like loops, conditionals, functions, variables (numbers, lists), input/output, and graphical display.

The file is the native save format used by AlgoBox. When you build an algorithm via its visual editor or by writing code in French (e.g. VARIABLE declarations, loops like "TANT_QUE", "POUR", conditionals), you can save your work; the software writes it into this format. You can later reopen it to continue editing or run the algorithm to verify its behavior. Exports from it can be made into text, HTML, LaTeX, PDF, PNG among others, but this format preserves the full structure, metadata, variables, and algorithm flow for ongoing editing.

Inside, the file is encoded in XML with UTF-8 encoding. It begins with the standard XML declaration, includes tags for description, functions, variable declarations, items for each instruction (like reading or assigning), and special markers such as DEBUT_ALGORITHME and FIN_ALGORITHME to frame the algorithm body. Named fields like "VARIABLES", "REPERE" (for coordinate systems), "ITEM ALGOITEM", fields for function code/status, and textual commands in French are all present.

Technical signature: the file starts with the bytes corresponding to "<?xml version=\"1.0\" encoding=\"UTF-8\"?>" at offset zero, and contains specific keywords such as FONCTION FCTCODE, FIN_ALGORITHME, ITEM ALGOITEM, VARIABLES, REPERE, among others, which reliably identify it.

How to open ALG files

Important: Different programs may use files with the ALG file extension for different purposes, so unless you are sure which format your ALG file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested nine different ALG openers which you will find listed below.

Last updated: August 18, 2026

Various apps that use files with this extension

These apps are known to open certain types of ALG files. Remember, different programs may use ALG files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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