Start With The Connector, Not The Sales Page
Broker choice begins with the wire that joins your software to their servers. That wire is the connector or API. If the connector is solid, orders reach the venue the way your rules expect, fills come back with the right stamps, and logs make sense on review. If the connector is flaky, nothing else matters. Identify the exact connector your software uses, confirm the broker supports that connector for the account type you plan to open, and ask if there are any feature gaps on that connector compared with the broker’s own app. The same firm can support different order sets and symbols depending on whether you connect by desktop bridge, REST plus websockets, FIX, or a plug-in built by a third party. Write down the path you will actually use and validate features on that path, not in general terms.
Common Software Families And Typical Broker Hooks
Different tools use different hooks. Knowing the family saves time and keeps you from chasing options you cannot use with your setup. The table below is a shorthand map; treat it as a starting point for your own matrix rather than a rule book.
| Software Family | Typical Broker Connection | Notes That Affect Compatibility |
|---|---|---|
| MT4 / MT5 expert advisors and scripts | Broker’s MT server login with trade permissions | Symbol suffixes (e.g. EURUSD.m), hedging vs netting modes, FIFO rules on some regions, min stop distance, partial fills behavior |
| cTrader cAlgo / cBots | cTrader ID linked to broker; Open API for data | Tick density can differ by account tier, depth feed optional, check stop limit support and server-side OCO |
| NinjaTrader, MultiCharts, Sierra, similar | Broker bridge or FIX; sometimes vendor’s own brokerage | Order simulators vary; verify bracket orders, ATM strategies, exchange holidays, and roll for futures |
| Custom bots and research stacks | REST + websocket stream, FIX 4.x/5.x, or vendor SDK | Auth scopes, rate limits, order throttles, last-look rules, retry policy, and idempotency keys matter more than brochures |
| Copy trading or signal followers | Broker plugin or hosted bridge | Latency between master and follower, size translation, and symbol mapping cause most mismatches |
Account Type, Symbols, And The Small Letters That Change Costs
Pick the account type before you evaluate fills because the account controls spread and commission structure. Raw spread plus commission accounts behave differently from all-in spread accounts, and your break-even hit rate moves with those costs. Confirm the exact symbol list on your intended account, including suffixes and contract sizes, because EURUSD, EURUSD.pro, and EURUSD-RAW may quote the same market with slightly different costs and min size. For indices, metals, energy, and exotics, confirm trading hours, margin schedule, and whether short side swaps are punishing. For futures, confirm exchange, contract month list, roll method, and whether server-side OCO is native.
Order Types And Rules Your Software Needs To Enforce
Walk through the tickets your software plans to send and match them to the broker’s real order book. Market, limit, stop, and stop-limit are the basics. Past that, check time in force, partial fill behavior, protection bands, min distance from price to stop, freeze levels near events, and whether OCO lives on the server or only in the client. If your tool relies on market on close or limit on close for equities, confirm support. If you trade sessions with gaps, confirm whether stops are market or stop-limit at open and how slippage is reported. Your goal is simple: every order your code emits maps one-to-one to a supported server action with a clear response path.
Data Feed Shape, Clock Sync, And The “Why Is My Candle Different” Problem
Spot FX and many CFDs aggregate quotes from several sources, so ticks and bars will not match across venues. That is normal. What you care about is consistency inside your own stack. Verify price precision, bar building rules, session calendars, and the close timestamp your software uses. Sync the VPS clock, record the offset, and store timestamps on request, acknowledge, and fill. If your strategy uses end-of-bar logic, confirm that the bar close event in backtests matches the event you get live. If your strategy uses tick-driven signals, confirm tick filters and throttles applied by the broker, because some accounts down-sample during quiet hours to save bandwidth.
Execution Quality: How To Test Without Guessing
Open a small live account and run a controlled plan for a week across London, New York, and Asia sessions. Use fixed size per ticket, fixed slippage allowance, and fixed rules for when you send market vs limit. Tag each order with symbol, side, size, entry plan, expected slippage, and a regime label such as quiet, normal, busy. After the week, compute request-to-ack times, ack-to-fill times, reject rates, price improvement rates, and the full slippage distribution by hour. Now you have the only scorecard that counts: how this broker behaves for your symbols on your connector at your hours. If the numbers look stable and the logs read clean, you keep going. If they wobble, change the connector or the venue before you scale.
Costs, Swaps, And Break-Even Checks You Should Do Up Front
A quick expected value check prevents rosy assumptions. Let average gain be G pips, average loss be L pips, win rate p, and round-turn cost C in pips including spread and commission. Then EV = p·(G − C) − (1 − p)·(L + C). With symmetric targets and stops where G = L = T, break-even sits at pBE = (T + C) / (2T). A broker that quotes wider at your active hours pushes C up and raises the bar you have to clear. Add swaps if you hold overnight. Some pairs quietly drain a strategy that looks fine intraday.
Risk Controls You Want On The Broker Side
Ask for hard limits you can set at the account level. A daily loss stop set by support, max net exposure by currency, and a per-ticket size cap save you from client bugs and fat-finger moments. Confirm margin call steps and liquidation policy in writing. If the firm offers guaranteed stop options on certain symbols, read the fine print on hours and distance. If you run multiple accounts from one machine, confirm whether sessions can run in parallel, and whether credentials allow IP whitelisting for a tighter security posture.
Regional Rules, Licensing, And The Paperwork You Don’t Want To Rush
Match your region to the license the broker holds and the products allowed under that license. Rules change what you can do with software. FIFO on some accounts affects how partial exits and hedges behave. Some regions limit leverage bands on retail accounts, which changes your lot sizing math. Read the product disclosure and the margin schedule for the exact account type you open, not just the headline. If the software depends on hedging, netting accounts will not be a fit unless you restructure the logic. If you plan to automate during events, confirm what the firm does around scheduled data; some venues widen protection bands or block certain order types during spikes.
Symbol Mapping, Contract Specs, And The Boring Bits That Cause Most Bugs
Build a symbol map inside your software that binds your internal names to the broker’s exact symbols, contract sizes, and pip precision. Store min and max size, step size, stop distance, and tick value per symbol. For indices and commodities, store session hours and holiday calendars. For futures, store month codes and roll triggers. On first connect, pull specs from the API if available and compare to your local map; fail loudly if anything changed. Most early-stage outages trace back to a stale symbol file or a surprise change in min size.
Paper, Sandbox, And Shadow Runs Before You Touch Real Size
Use a paper or sandbox account if the broker offers one, but assume its fill behavior is kinder than live. The best pattern is a short paper run to shake out logic, followed by a small live run at your true hours with recorded logs, then a shadow A/B test where the new version runs beside the old one for a week. Promote only after live distributions match your expectations. Keep a rollback plan and a one-button kill switch bound to a hotkey. Store a short incident note any time you hit that switch so you can fix the cause later with a clear head.
Binary Options And Other Fixed-Payout Products
If your software trades fixed-payout contracts, broker choice is tighter. Confirm strike reference, expiry windows, payout tables by asset and by expiry length, and whether late cancellation is allowed. Your backtests need those tables baked in; small payout changes move the break-even hit rate a lot. Ask for a clean export of request, accept, and settle stamps with the price source at settle. Without those stamps you cannot reconcile results when a close decision drifts a second or two.
Support, Status Pages, And People You Can Actually Reach
Ask how outages are announced, where the status page lives, and what the incident response window looks like for API users. If you plan to trade through the night, confirm support hours and channels. A human who knows the API and can read a correlation ID from your logs is worth more than a glossy banner. Keep a small list of names and emails for escalations and test them once with a harmless ticket so you know the path works before you need it.
Security And Operational Hygiene
Store API keys in an encrypted vault and restrict scopes to read, trade, or funding as needed. Enable multi-factor and IP allowlists if offered. Patch the VPS on a schedule, rotate keys, and back up configs and logs daily to a second region. Keep credentials out of screenshots, chat windows, and debug prints. Boring habits here prevent the most expensive mistakes you can make, the ones that happen before the first trade.
A Simple Validation Plan You Can Reuse Across Brokers
Create a short, repeatable script. Connect with minimal permissions and pull specs, symbol list, margin schedule, and costs. Place a tiny market order, a tiny limit order, and a stop order on a liquid pair during quiet hours and record stamps. Cancel a working order, modify a stop, and trigger an OCO to prove the server owns the link. Hold one position overnight to observe swap. Export logs, rebuild fills from the broker’s data, and check that your internal book equals the statement to the cent. If this small plan passes cleanly, you scale. If it does not, you stop. No drama needed.