Installing Custom Indicators and EAs on MT4/MT5

The MetaTrader ecosystem's real power is its community-built indicators and EAs — but installation trips up almost every beginner.

File types you will encounter

Extension	Type	Where it goes
.mq4 / .mq5	Source code	MQL4/MQL5 folder, must be compiled
.ex4 / .ex5	Compiled binary	Same folder, runs directly
.set	EA parameter preset	MQL5/Presets
.tpl	Chart template	Templates folder

Compiled files (.ex4/.ex5) are the most common downloads because authors protect their source code. Source files let you edit logic but require compilation.

Method 1: The safe manual install

1. Open MT4/MT5.
2. Click File → Open Data Folder.
3. Navigate to MQL4/Indicators (or MQL5/Indicators).
4. Copy your .ex4/.ex5 file into this folder.
5. Restart the terminal (or right-click Navigator → Refresh).
6. Expand Indicators in the Navigator panel and drag it onto the chart.

For EAs, use MQL4/Experts or MQL5/Experts instead. Scripts go in MQL4/Scripts.

Method 2: Compile from source

1. Open the source file (.mq4/.mq5) in MetaEditor (press F4 from MT4).
2. Press F7 to compile.
3. Fix errors if listed at the bottom of the editor.
4. The compiled .ex4/.ex5 lands in the correct folder automatically.

Enabling automated trading

EAs will not trade until you:

1. Click the AutoTrading button on the toolbar (it turns green).
2. Check Tools → Options → Expert Advisors → Allow automated trading.
3. Ensure the chart's Common tab has "Allow live trading" checked.

A smiley face in the top-right corner of the chart confirms the EA is running live.

Common errors and fixes

• "DLL not found": enable Allow DLL imports in the EA's Common tab and ensure the DLL is in MQL4/Libraries.
• Trade failed - disabled: AutoTrading is off or the broker blocks EAs.
• Indicator not in Navigator list: wrong folder, or the file is for the other platform (MT4 indicators do not load on MT5).
• Compiled but nothing happens: timeframes or symbols do not match — open the inputs panel (Ctrl+I).

Security warnings

• Never run a downloaded EA that you cannot identify. Malicious .ex4 files can read account credentials.
• Scan .ex4/.ex5 files for unusual network calls (rare but possible).
• Prefer paid or open-source tools over "free cracked" EAs that promise unrealistic returns.
• Always test on a demo account for at least two weeks before going live.

Practical beginner workflow

1. Pick one indicator (a moving average ribbon is enough).
2. Compile it from source so you understand MetaEditor.
3. Save a chart template (Charts → Template → Save Template) so you can reuse the layout.
4. Only then move to a free EA like the MetaQuotes sample MACD EA to learn automated trading mechanics.

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Next: learn why demo testing an EA for weeks beats trusting a backtest.