For the technically inclined, you can view an EX4 in a hex editor (e.g., HxD) and manually reconstruct the logic. This is not practical for most traders, but it's 100% free and virus-free.

Steps:

This method takes days or weeks for a simple indicator and is only for educational reverse engineering.

Let's say you miraculously get an MQ4 file from a free converter. Here is what you actually get:

// Original logic (hidden by developer)
double CalculateRSI() 
   return iRSI(NULL, 0, 14, PRICE_CLOSE, 0);
// What decompiler gives you
double var_abc() 
int a = 14;
int b = 0;
double c = iRSI(NULL, 0, a, PRICE_CLOSE, b);
return c;

But more realistically:

double a1b2c3() 
   // Missing include <stdlib.mqh>
   // Undefined function xyz()
   // Goto labels everywhere
   return 0;

You cannot fix this without understanding the original EA’s logic anyway. So if you are a competent programmer, you might as well rewrite the EA from scratch by observing its behavior – which is legal and cleaner.

| Aspect | Verdict | | :--- | :--- | | Does it work? | For modern EX4s, no. For ancient ones (pre-2015), maybe 10% success. | | Is it safe? | Extremely dangerous – most free tools contain malware. | | Is it legal? | No – violates MetaQuotes terms and copyright laws. | | Is it worth it? | No. Even if you succeed, the code is a broken mess. |

Before trying to convert a file, you must understand what you are dealing with.

A few websites offer free EX4-to-MQ4 conversion. However, they are extremely risky because you upload your EX4 to an unknown server.

Popular (but not recommended) free online converters:

Risks:

Verdict: Avoid free online converters unless the EX4 is public/open-source.