What is the EX4 to MQ4 Decompiler Tool

A dedicated program, the EX4 to MQ4 decompiler built to convert in reverse the code compiling action for programs used on the MetaTrader 4 (MT4) trading platform.

Function and Files

The MetaTrader 4 platform uses the MetaQuotes Language 4 (MQL4) for creating custom Expert Advisors (EAs), indicators, and scripts.

The MQ4 file holds the core source code (human-readable code) written by the developer. This is what you can open and edit in the MetaEditor.

The EX4 file is the ready-to-run, compiled file of the MQ4 code. Developers compile MQ4 files into EX4 files for distribution, as the compiled version executes more quickly on the trading terminal and protects the original source code from being easily viewed or modified.

The decompiler attempts to convert the compiled EX4 file back into a close approximation of the original MQ4 source code.

Purpose and Context

The primary reasons developers or traders seek to decompile EX4 files include:

Code Recovery: Recovering lost source code (MQ4) for an EA or indicator when only the compiled EX4 file remains e.g., after a computer crash.

Modification/Debugging: Gaining source code access to adjust, debug, or change the logic of an indicator or EA.

Analysis: Analyzing the trading logic and algorithms used by a compiled program.

Limitations and Ethics

Key factors to note include:

Newer MT4 Builds: Modern versions of MT4 (Build 600 and later, released since 2014) use a different and more secure compiling technique, making decompilation significantly more difficult, if not impossible, for most commercial decompilers.

Incomplete Code: Decompilers often produce code that is obfuscated, incomplete, or hard to read, requiring extensive manual effort to restore functionality.

Legal/Ethical Issues: Decompiling commercial EAs or indicators to steal or replicate the underlying strategy is generally a violation of the developer’s IP rights and is often considered a breach of law or ethics.