MetaQuotes offers no official decompiler. However, if you are the original author and lost the MQ4, you can recompile from a backup or use version control (e.g., GitHub, GitLab).
If you must decompile, you are likely looking for specialized software rather than a pure "upload-download" website. Use Specialized Decompiler Software:
Feasibility and Risks of Reverse Engineering Compiled MQL4 Code: An Analysis of Online "EX4 to MQ4" Conversion Tools
MetaQuotes offers no official decompiler. However, if you are the original author and lost the MQ4, you can recompile from a backup or use version control (e.g., GitHub, GitLab).
If you must decompile, you are likely looking for specialized software rather than a pure "upload-download" website. Use Specialized Decompiler Software:
Feasibility and Risks of Reverse Engineering Compiled MQL4 Code: An Analysis of Online "EX4 to MQ4" Conversion Tools