Can You Trust an EA You Can't Read? Closed-Source (.ex5) EAs

Can You Trust an EA You Can't Read?

Most commercial EAs are distributed as a compiled .ex5 (MT5) or .ex4 (MT4). These are binaries, so you cannot read the logic inside. Is it averaging down? Is there a hidden martingale? What conditions does it enter on? As long as the source is closed, the code can't tell you.

So how are you supposed to trust an EA you can't see inside?

Why closed source is normal

First, a premise: keeping the source closed is not, in itself, shady.

• An EA's logic is the developer's intellectual property; publish it and it is trivially copied.
• If you sell it, protecting the internals is simple economic sense.

So we too distribute our EAs as compiled .ex5 (both the free versions and the paid MQL5 Market versions). "Closed source = suspicious" is not the reality. The real issue is that since you can't read the code, trust has to be established by something other than the code.

If you can't read it, judge by verification

If you can't read the source, judge the EA not by what it does internally but by what it did — that is, by external verification data.

1. Real-tick backtest: is the model real ticks (the real-ticks article)? Hidden thin-margin logic is exposed on real ticks.
2. Trade count: 500+ across multiple regimes (the sample-size article).
3. Equity drawdown: equity, not balance. Averaging and grid reveal themselves in equity DD (the drawdown article).
4. Year-by-year P&L: not concentrated in one year.
5. Third-party-verified live record: a reinforcing signal if present (the track-record article).

Even without reading the code, if this external data is all present the EA's true nature is fairly visible. Conversely, an EA that discloses none of it and just says "the internals are secret, but it's profitable" offers nothing to back the trust.

Checking behaviour when you can't read the source

Even without the source, you can check an EA's discipline yourself:

• Check the trade list in the Strategy Tester: is there an SL on every trade, are positions never stacked in the same direction, does the lot never increase after a loss?
• Compare with the published data: we publish real ticks, trade count, equity DD and year-by-year P&L for our EAs on the verification page.

Donchian Trend Engine (free EA, USDJPY H1)

Summary

• Most commercial EAs ship as .ex5 / .ex4; the logic can't be read.
• Closed source is legitimate IP protection (our EAs are also distributed as .ex5).
• Since you can't read it, judge by external verification (real ticks, trade count, equity DD, year-by-year, live record).
• An EA that discloses no verification data has nothing backing the trust.
• Even if you can't read the source, the tester trade list and published data let you verify behaviour.

Related: Backtest profitable but losing live · How to tell if a live track record is real · How to spot scam EAs and hype