14 Aug 2025
“How to (Legally) Decompile EX4 Files to MQ4: What You Need to Know”
How to (Legally) Decompile EX4 Files to MQ4: What You Need to Know
Meta Description:
Discover the legal considerations and safe methods for converting EX4 files to MQ4 format in MetaTrader 4. Learn what’s allowed, what’s risky, and how to protect your trading code.
Introduction
If you’ve been trading with MetaTrader 4 (MT4) for a while, you’ve probably come across EX4 files — the compiled format of Expert Advisors (EAs), indicators, and scripts. Sometimes, you may need to convert an EX4 file back into MQ4 (its original source code format) for updates, bug fixes, or learning purposes.
Here’s the catch: decompiling EX4 files can cross legal and ethical lines if you’re working on code you don’t own. In this guide, we’ll explore what’s legal, what’s not, and the proper way to “decompile” without getting into trouble.
Understanding EX4 and MQ4
Before we talk about decompilation, let’s break down what these files are:
• MQ4 file: The original source code written in MQL4 (MetaQuotes Language 4).
• EX4 file: The compiled version of MQ4, which runs in MT4 but hides the human-readable code.
When a developer compiles an MQ4 file into an EX4, it becomes much harder to reverse-engineer — partly to protect intellectual property.
Is It Legal to Decompile EX4 Files?
Here’s the short answer: Yes, but only in certain cases.
✅ Legal situations include:
• You wrote the original MQ4 code yourself but lost the source file.
• You have explicit written permission from the original developer to decompile it.
• The EX4 file is open-source or under a license that allows reverse engineering.
❌ Illegal situations include:
• Decompiling an EX4 you purchased without permission.
• Reverse-engineering someone else’s commercial EA or indicator for resale or distribution.
• Downloading cracked EX4 decompilers to bypass licensing.
Breaking these rules can violate copyright laws, software agreements, and even MetaQuotes’ terms of service.
Safe, Legal Ways to Get Your MQ4 Code Back
Instead of using shady “EX4 decompilers” from random websites (many are malware), consider these safer, legal approaches:
1. Contact the Original Developer
If you bought or commissioned the EX4 file, ask the developer for the MQ4 version. Many will share it if you can prove purchase.
2. Use Backups or Old Email Attachments
You might already have an older MQ4 version saved on your computer or in your email history.
3. Recreate the Code
If it’s your own EA or indicator, you can rewrite it from scratch. This also gives you the chance to optimize and improve your logic.
4. Hire a Licensed MQL4 Developer
Some developers offer legal EX4 recovery services for authorized owners. They’ll request proof that you own the file.
Why Most EX4 Decompilers Are Risky
• Malware and viruses: Many downloadable EX4 decompilers infect your system.
• Poor accuracy: Decompiled MQ4 code is often messy, incomplete, or unreadable.
• Legal trouble: Even if you don’t distribute it, reverse engineering without permission can land you in legal disputes.
Protecting Your Own EX4 Files
If you’re a developer, you can make your EX4 harder to decompile:
• Use MetaTrader’s latest compiler (Build 600+).
• Implement DLL encryption for sensitive logic.
• Add license keys and account binding.
Final Thoughts
Converting EX4 to MQ4 isn’t always illegal — but it’s a fine line. If you’re working with your own code or have permission, it’s completely safe. If not, you’re entering dangerous territory that can hurt your trading reputation and expose you to lawsuits.
Whenever possible, stick to legitimate recovery methods or simply rebuild your indicator/EA from scratch. You’ll avoid legal headaches and ensure your trading tools are secure.
