What is a .set file in MT5? Loading, saving and versioning EA presets

A .set file stores an Expert Advisor's input values. Here's how to load, save and version presets in MetaTrader 5, and why a preset is only valid for the market it was tuned on.

The short answer

A .set file is a plain-text list of an Expert Advisor's inputs, such as lot size, stop-loss, trading hours and filters. It lets you save a configuration and load it again, or share it, without retyping every input. The EA's code decides how it trades. The .set file decides with which settings.

Loading and saving

In the Strategy Tester or on a chart, open the EA's Inputs tab and use Load or Save. MT5 keeps presets in MQL5/Presets by default. When you attach an EA to a live chart, always open the Inputs tab and confirm the values: loading the wrong preset is one of the most common and expensive mistakes.

Version your presets

Name presets with the symbol, timeframe and a version, for example XAUUSD_M5_v1.2.set. When results change, you'll know whether the code, the preset or the market changed. Keep the Strategy Tester report that validated each preset next to it: a preset without its report is an untested claim.

A preset belongs to a market regime

Presets are usually tuned on a specific symbol, timeframe and period. After a big change in volatility or spreads, re-run the preset on recent real-tick data before trusting it again. A robust preset sits in a stable region, where nearby values also work, rather than on a single sharp peak.

Questions

Can I use a .set file from another EA?: No. Input names must match the EA exactly. MT5 silently ignores inputs it doesn't recognise.
Is a .set file safe to open?: It's plain text with input values, not code. You can open it in any text editor to check what it sets.

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