What actually matters when picking a broker to automate

Choosing a broker for manual trading and choosing one to automate are different exercises. Commission still matters, but for automation four other things tend to matter more.

Order types the broker actually supports

Bracket orders — an entry with a stop and target attached — let the broker manage your exit even if your signal source goes quiet. Not every broker supports them; several only accept simple orders, which means your stop loss has to be sent as a separate signal rather than living with the entry from the start.

Whether a real paper environment exists

Some brokers offer genuine simulated trading with live-ish data. Others don't offer paper trading at all, which means your only rehearsal option is a small live position — a meaningfully different risk profile than testing on paper first.

What market data the API actually gives you

A few broker APIs don't expose live quotes or open-position P&L at all, even though the trading side works fine. That's rarely a dealbreaker, but it changes how you monitor a strategy day to day.

Authentication that matches how you operate

Some brokers hand you a long-lived API key. Others use OAuth tokens that expire on a schedule — anywhere from auto-refreshing indefinitely to needing manual reconnection every couple of weeks. If a strategy needs to run completely unattended, that expiry schedule is worth checking before you commit to it.

Start on paper, regardless

Whichever broker you pick, the fastest way to learn its specific quirks is to run a strategy against its paper environment — or ezpztrader's own simulator if the broker doesn't have one — before a single live order goes out.