If you lose your original source code or want to modify an older indicator, you need to turn that EX4 file back into an MQ4 file. This process is called decompiling.

The output from a decompiler is best used as a starting point for learning or recovery, but it will always require significant manual effort to clean up, rename variables, and verify its logic.

For the technically adept, more powerful, albeit complex, methods exist. Professionals and advanced hobbyists sometimes use sophisticated reverse engineering tools like to analyze EX4 files. This method is far more involved than using a dedicated decompiler and is often used for educational purposes, such as understanding obfuscation techniques or debugging custom code when the source is unavailable. However, this approach requires a deep understanding of assembly language and low-level programming concepts, making it impractical for the average MT4 user.

The most responsible and secure approach is to always seek the original MQ4 source code from the developer whenever possible. If you choose to use a decompiler, do so with a full understanding of the risks and always prioritize the security of your system. Ultimately, the knowledge and skill to build your own strategies are far more valuable than any piece of decompiled code.

Instead of risking your computer security with a "crack," try these legitimate approaches:

Converting MQ4 to EX4 is a standard, one-click process. Converting EX4 back to MQ4, however, requires reverse engineering. Is It Legally and Ethically Safe to Convert EX4 to MQ4?

If you need editable source for an expert advisor/indicator, here are lawful alternatives: