Because modern decompilation is technically complex and often requires manual human intervention to fix broken code, fully automated free software effectively does not exist for modern files. Today, decompilation is usually a paid service provided by reverse engineers who use private, sophisticated tools, rather than a downloadable free app.
If free decompilers fail (and they likely will for modern EAs), consider these alternatives:
Ethical alternative: If you need to modify an EA, contact the original developer for source code under a paid license.
Prior to early 2014 (specifically MetaTrader Build 600), EX4 files were compiled in a relatively simple format. During this time, decompilation was straightforward. Free tools were widely available that could successfully reverse-engineer EX4 files into readable MQ4 code with high accuracy. As a result, code theft and unauthorized modifications were rampant. Free Ex4 To Mq4 Decompiler Software Applications
If you want to modify an EA but only have the EX4 file:
Stay safe, and happy coding!
Disclaimer: This post is for educational purposes only. Decompiling software you do not own is illegal in many countries. The author does not endorse software piracy or downloading unverified executables. Prior to early 2014 (specifically MetaTrader Build 600),
Even if the decompiler isn't a virus, the output is usually terrible. Decompiled code often looks like this:
You will spend 20 hours fixing the decompiled mess rather than rewriting the EA from scratch.
Decompilers must reconstruct loops, conditionals, and function calls from linear bytecode. Free tools use naive pattern matching. Professional decompilers (e.g., Hex-Rays for C++) use advanced graph algorithms. Free EX4 tools use neither—they produce "spaghetti code" with goto statements everywhere. Stay safe, and happy coding
In response to intellectual property theft, MetaQuotes (the developer of MT4) drastically overhauled the compiler architecture in Build 600. They introduced heavy encryption, obfuscation, and a new bytecode structure.
For files compiled after Build 600, the situation changed drastically: