If you are a professional managing client funds or relying on a commercial EA, free decompilation is too risky. The hidden bugs, malware threats, and legal liabilities outweigh the cost savings. Instead, either pay for a reputable decompilation service or (better yet) rewrite the strategy from scratch based on its observed behavior.

Before attempting any conversion, you must understand what these files actually are:

Converting EX4 back to MQ4 is essentially trying to "reverse-engineer" the compiled code. Is It Possible to Convert EX4 to MQ4 for Free?

Converting EX4 to MQ4 can be a useful process for modifying, understanding, or recovering EA or indicator source code. While there are online converters and software available that offer this service for free, there are limitations and risks to consider. Always use caution when decompiling EX4 files, and make sure to test the converted MQ4 file thoroughly before using it in a live trading environment.