Specifically aimed at .ex4 files, which are the compiled versions of .mq4 source files.
Decompiling commercial EAs to remove licensing or distribute them for free is considered illegal in most jurisdictions and a violation of copyright law. Ex4 To Mq4 Decompiler 4.0.432 - Updatedl
If you need to modify an indicator or EA without the source code, there are safer methods: Specifically aimed at