If you only need to use an indicator's data in another Expert Advisor (EA), you can use the iCustom function in MQL4 to pull values from the .ex4 file without needing the source code.
Instructions for students:
Some tools found in forums (e.g., "EX4-TO-MQ4 Decompiler 4.0.432") only work for extremely old files compiled over a decade ago and are largely obsolete for current trading robots. The Risks of Online "Converters" how to convert ex4 file to mql4
The code within an EX4 file is the intellectual property of the developer. Decompiling proprietary software without authorization is generally considered a violation of copyright law and software license agreements (EULA). Most EULAs explicitly prohibit reverse engineering. If you only need to use an indicator's
This is the most common situation. You wrote or purchased an EA, used it for months, and then lost the source code due to a hard drive crash or accidental deletion. The EX4 is still running on your charts. You wrote or purchased an EA, used it