Are forex trading bots legal?

There is no general prohibition on trading with software. Institutional trading is overwhelmingly automated, retail platforms include an Expert Advisor environment as a standard feature, and brokers advertise EA compatibility as a selling point. The legality question is almost always really a permissions question.

Broker terms are where restrictions actually appear, and they are usually narrow rather than blanket. Common ones prohibit latency arbitrage, exploiting mispriced quotes, or trading strategies designed to abuse a specific execution model. A rule-based system trading gold on a public feed does not resemble any of these.

Prop firms are stricter and more variable. Some permit EAs freely, some prohibit them entirely, some allow them only on funded accounts and not during evaluation, and some prohibit copying the same trades across multiple accounts. This is a per-firm question with no general answer — see can you use an EA on a prop firm account.

The US question is about the instrument, not the bot

For traders in the United States the constraint is different and more fundamental. Retail access to spot gold CFDs is heavily restricted domestically, and most offshore brokers offering XAUUSD do not accept US residents. That has nothing to do with automation — a manual trader faces exactly the same wall.

This is why the practical US route for an MT5 gold bot is a prop firm account rather than a retail brokerage one. The full explanation is in can US traders use MT5 trading bots.

None of this is legal advice, and rules differ by state and by account type. Check your own broker's terms and your own jurisdiction rather than relying on a general statement.