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GUIDE · 7 MIN READ

Forex expert advisors explained: what an EA is, MT4 vs MT5, the MQL5 Market and how to judge one

BotIndex editorial team · Updated 6 Nov 2026 · Editorial policy

SHORT ANSWER

A forex expert advisor (EA) is a program that runs inside MetaTrader 4 or 5 and places trades on your broker account by fixed rules. You can write one, buy or rent one on the MQL5 Market, or download free code. Judge an EA by a verified live record and its drawdown, avoid martingale designs and unofficial download sites, and test it on a demo first.

What are forex expert advisors?

Forex expert advisors are trading robots that run inside MetaTrader. A forex EA is a program, written in the MQL4 or MQL5 language, that reads prices on a chart and opens, changes and closes trades on your broker account according to its rules. When people ask what “EA in trading” means, this is it: Expert Advisor is simply MetaTrader’s name for a trading bot.

An EA does not have special knowledge of the market. It does exactly what its code says, every time, including the bad parts. MetaQuotes, the company behind MetaTrader, says it is a software developer and does not provide brokerage services; the terminal is free and you trade through a broker that licenses it (MetaTrader 5 review).

BotIndex mainly reviews crypto trading bots. For forex we review the platforms, not individual EAs, and we do not recommend any EA, broker or currency. For the wider picture of forex robots, cBots and signal copying, start with our automated forex trading guide.

MT4 vs MT5 expert advisors

MetaTrader 4 and MetaTrader 5 are separate platforms, and both are still offered. The MT4 site still offers free downloads and announced Build 1490 on 2 October 2026 with “several important security enhancements” (MetaTrader 4). MetaTrader 5 describes itself as a multi-asset platform for forex, stocks and futures, depending on what your broker offers.

MetaTrader 4 MetaTrader 5
EA language MQL4 MQL5 (.mq5 source, compiled to .ex5)
Markets Set by your broker Forex, stocks and futures, set by your broker
Built-in marketplace Yes, buy or rent robots Yes, MQL5 Market
Status Still offered and updated Still offered and updated

The practical point: MT4 expert advisors and MT5 expert advisors are written in different languages, so an EA built for one generally will not run on the other without being rewritten. When you buy or download an EA, make sure it matches the platform your broker gives you. If you see “stock market expert advisor,” that usually means an MT5 EA trading share CFDs or stocks through a broker that offers them.

How to install and run an EA (high level)

MetaTrader’s own help covers the details (MetaTrader 5 automated trading help). In outline:

  1. Get the EA from an official channel. The MQL5 Market (built into the terminal), the MQL5 Code Base of free examples, or your own code written in MetaEditor.
  2. Put it in the right folder. EA files live in the MQL5/Experts folder. Source files (.mq5) must be compiled into .ex5 files in MetaEditor before they run.
  3. Attach it to a chart for the currency pair and timeframe it was designed for, and set its inputs, especially lot size and any risk settings.
  4. Allow algo trading in the terminal. MetaTrader notes that disabling Expert Advisors in settings “only prohibits Expert Advisors from trading.”
  5. Keep it running. The help says robots and signals “require constant connection to a trade server and uninterrupted power supply,” which is why MetaTrader sells virtual hosting (MetaTrader 5 Virtual Hosting). If your computer sleeps, the EA stops managing open trades.

About the “MT5 automated trading robot free download APK” searches: the official mobile apps come from metatrader5.com and the Apple and Google app stores. Running EAs is described for the desktop terminal and virtual hosting, not the phone. An APK from an unofficial site is unnecessary and is exactly the kind of file you should not install.

The MQL5 Market (MT4 market and MT5 market)

The MQL5 Market is MetaQuotes’ official EA store, reachable from inside both terminals. People also call it the MT4 market or MT4 marketplace. The MT4 site says you can “buy or rent trading robots and technical indicators” there. Most products are made by third-party sellers, not by MetaQuotes.

What the Market rules say, in short:

  • Automatic testing, not vetting. Products pass automatic pre-testing in the Strategy Tester, and the administration does only a formal check. Passing “does not guarantee future results.”
  • No refunds. Purchases cannot be returned. If fraud or a misleading description is found, the seller is blocked and buyers get the sale funds back.
  • Rent or demo first. Sellers can offer a one-month rental, and demo versions run in the Strategy Tester but not on a live chart.
  • Activations. A purchase includes 5 to 20 activations, tied to specific hardware.
  • Banned claims. Sellers may not promise or hint at profits, or present backtests as real trading results. Neither the seller nor MQL5 is liable for your trading losses.

Prices vary widely. We have seen listings priced around 899.95 USD one-off and yearly rentals, and some listings openly use grid or martingale methods. Any return figures on listings are the sellers’ own claims, not verified by BotIndex.

MQL5 Signals is a separate service: instead of running an EA, you copy another account’s trades for a monthly fee. Its rules say a paid subscription cancelled by the subscriber “is not refunded” and that the subscriber “accepts all execution risks” (MQL5 Signals rules). See our copy trading guide for how copying works.

Why “free EA download” sites are risky

Searches like “free forex EA,” “MT5 EA free download” or “MT4 automated trading robot free download” lead to a lot of forums, file lockers and Telegram channels. Three problems come up.

Malware. Fake free trading software is a proven way to infect traders’ computers. Bitdefender documented a campaign promising “free access” to TradingView Premium and other trading platforms through Meta, Google and YouTube ads; the download installed a stealer that can collect passwords and cookies, log keystrokes and steal crypto wallet data (Bitdefender Labs). Its advice: download software only from official websites. A compiled EA, or an “installer” that comes with it, is code running on the same machine as your broker login.

Scams. The CFTC warns about trading bots sold with “unreasonably high or guaranteed returns” or “100 percent ‘win’ rates,” and describes a forex bot scheme that used MetaTrader demo accounts to show false balances (CFTC press release 8854-24). “Free” EAs are often the hook for a paid course, a signal group or a recommended offshore broker.

Cracked paid EAs. Copies of paid Market products with the licence protection removed break the seller’s licence and are impossible to verify. You have no idea what was changed.

If you want a free EA, use the MQL5 Code Base, the free section of the official Market, or write your own simple one in MetaEditor.

How to evaluate an expert advisor

Whether you are looking at the “best MetaTrader 4 expert advisor” in someone’s ranking or a forex EA store listing, check the same things.

  1. Verified live record vs backtest. A backtest is a simulation, and optimised settings can fit past noise. A real-money account tracked by a third party for a year or more, including a losing stretch, is worth far more than a perfect backtest chart.
  2. Maximum drawdown. The largest peak-to-trough loss shows how much pain the EA has produced. A smooth equity curve with tiny drawdown often means losing trades are being held open, not closed.
  3. Martingale or grid logic. Martingale increases position size after losses; many retail EAs combine it with a grid of averaging orders. Look for inputs like “lot multiplier,” “recovery” or “basket close,” and for no stop-loss. These designs win often and lose big.
  4. Costs and conditions. Scalping EAs depend on low spreads and fast execution. Results on the seller’s broker may not repeat on yours.
  5. The seller. Profit promises break the Market’s own rules. Treat them as a warning, not a feature.

Safer ways to try an EA

  1. Backtest on real ticks. MetaTrader’s Strategy Tester has an “every tick based on real ticks” mode and a forward-testing option meant to “avoid parameters fitting in certain areas of historical data” (Strategy Tester help).
  2. Run it on a demo account with your broker for several weeks, through some volatile news.
  3. Rent before buying if the seller offers a monthly rental.
  4. Go live with the minimum size and a written drawdown limit at which you switch it off. Use our position size calculator to check what each trade risks, and our trading risk management guide for the wider rules.

For how MetaTrader compares with cTrader’s cBots, see our cTrader review and the best forex trading bots page.

FAQ

What does EA mean in trading?

EA stands for Expert Advisor, MetaTrader's name for a trading robot. It is a program written in MQL4 or MQL5 that can analyze prices and open, modify and close trades automatically while the terminal is running. Other platforms use other names, such as cBots on cTrader.

Are free forex EAs safe?

Free EAs from the official MQL5 Code Base or Market are at least distributed through MetaQuotes' own channels. Files from forums, Telegram groups or download sites are not checked by anyone you can hold accountable, and fake free trading software has been used to spread password-stealing malware. Even a clean free EA can still lose money, so test it on a demo account.

Can I run an EA on the MT5 mobile app?

MetaTrader's help describes running Expert Advisors in the desktop terminal, where EA files live in the MQL5/Experts folder, or on rented virtual hosting for 24/7 operation. The mobile apps are best treated as a way to monitor and trade manually. Download the apps only from metatrader5.com or the official app stores, never as an APK from a third-party site.

Can I get a refund for an EA bought on the MQL5 Market?

The MQL5 Market rules say purchases cannot be returned. If fraud or a misleading description is found, the seller's account is blocked and sale funds go back to buyers. That is why the rules point to renting a product for a month or testing a demo version in the Strategy Tester before buying.

Do expert advisors work for the stock market?

MetaTrader 5 is a multi-asset platform that can trade forex, stocks and futures, so an EA can trade any instrument your broker offers in MT5. Which stocks you can trade, and at what cost, depends entirely on the broker. The evaluation rules in this guide apply the same way.

Sources

Not financial advice. Trading bots do not remove market risk.