The broker is the part of an algorithmic system you cannot backtest away. The model is fixed, but the cost and the quality of every fill are set by the broker. Choosing one is a due-diligence exercise, not a preference, and the criteria do not change just because a provider offers good marketing.
This article covers what actually matters for Expert Advisor trading, how to measure it on a demo account, and a checklist you can apply to any broker. At the end we note which broker we test on and why, briefly, the criteria come first, and they are portable.
1. The execution model
Two broad models exist. A market maker (or B-book) broker takes the other side of your trade and earns when you lose; typically it hedges internally or passes flow to a liquidity provider beyond a threshold. An STP/ECN broker routes orders to liquidity providers and earns from commission or a spread markup. In practice most retail brokers run a hybrid of the two.
What matters to an EA is not the label but observable behaviour: average fill latency, how often the filled price differs from the requested price, and how spreads behave around news. Measure those three and ignore the marketing language.
2. Spread vs commission: compare the total cost
Pricing comes in two shapes. Some accounts quote a spread with no separate commission; others quote a raw spread plus a fixed commission per lot per round turn. To compare them you have to normalise both to one number.
On EURUSD, one standard lot and one pip are worth $10 per pip.
- A spread-only account quoting 0.68 pips with no commission costs about $6.80 per round turn.
- A raw-spread account quoting 0.0 pips plus $4.50 per lot round turn costs $4.50.
- The same broker's higher-tier account at $3.50 per lot round turn costs $3.50.
Spread and commission are not alternatives, they are two ways of pricing the same round turn. Add the swap or rollover rate for anything held overnight, and remember that spreads widen around news releases, which is exactly when some EAs trade.
3. What the platform lets your EA do
If a strategy uses machine-learning models, external data, or native libraries, the terminal's permissions decide what is possible:
- WebRequest, normally restricted to a whitelist of URLs. If your EA calls an API, confirm you can add that endpoint.
- DLL imports, required by some libraries, blocked by some brokers.
- ONNX runtime, lets MT5 run a trained model file directly. Availability depends on the terminal build and whether the broker enables it.
- Strategy Tester with real tick data, needed for credible backtests.
Test all four on a demo before committing. One blocked permission can invalidate a strategy you have already built.
4. Regulation, and which entity you actually onboard with
A group may hold several licences, but you open an account with one legal entity, and which entity that is depends on where you live. The protections differ between them, so read your entity's terms rather than the group's global page.
- ASIC (Australia) and FCA (UK) entities give retail clients negative balance protection, you cannot lose more than your account balance.
- CySEC (Cyprus) covers much of Europe, with DFSA (Dubai), FSCA (South Africa), and FSC (Mauritius) covering other regions.
- Client funds should be held in segregated accounts.
Leverage is a related question. Some entities permit up to 1000:1, which raises the speed at which a leveraged position can be liquidated. Negative balance protection does not make high leverage safe; it only caps the loss at the balance.
5. Where the trade server sits
Latency is distance. An EA on a VPS in the same city as the broker's trade server has a fraction of the round-trip time of one running over a home connection. Before choosing a VPS, find the broker's server location and match it. This is one of the few execution improvements you can actually measure.
Testing a broker before moving money
A demo account costs nothing and answers most of the questions above. Run it for several weeks and record:
- Fill quality. Log the requested price against the filled price for every order. Average slippage in pips is the number that matters.
- Latency. Time from order send to fill, measured in the sessions your EA actually trades.
- Spread behaviour. Spread on your instruments during those sessions, including through one news release.
- Permission tests. A WebRequest call to a non-whitelisted URL, a DLL call, and an ONNX model load.
- Financing. The cost of holding one position through a rollover.
The checklist
- Total round-turn cost, spread plus commission, on your main instruments.
- Measured average fill latency and slippage, not advertised figures.
- WebRequest whitelist, DLL imports, ONNX availability, tick-data testing.
- The specific regulated entity for your country, and whether retail clients get negative balance protection.
- Segregation of client funds.
- Swap rates for positions held overnight.
- VPS and trade-server locations.
- Minimum deposit and account currency.
- Whether EAs are permitted, and with what restrictions.
The broker we use
We run our testing on Axi. Stating it plainly, because the criteria above are the reason rather than the conclusion:
- Full MT5 support with no DLL or WebRequest restrictions on our accounts, and ONNX runtime available.
- A Pro account quoting raw EURUSD spreads around 0.0 pips plus $4.50 per lot round turn. The Standard account quotes roughly 0.68 pips with no commission. A higher-tier Elite account is $3.50 per lot round turn.
- Measured average execution of 29 ms in our testing, with 450+ instruments available.
- Regulated by ASIC, FCA, and CySEC, plus DFSA, FSCA, and FSC Mauritius. Which entity applies depends on your residency, retail clients under the ASIC and FCA entities get negative balance protection, and client funds are segregated.
- Leverage available up to 1000:1, which is high; size positions accordingly. The recommended minimum deposit is $100.
None of that makes it the only reasonable choice. If your current broker passes the checklist, there is no reason to move.
Where this applies
The checklist is broker-agnostic, execution model, cost per round turn, terminal permissions, entity regulation, and server proximity are the same questions for any provider, and you can score a different broker against them exactly as we score ours. We test on Axi because it satisfies those criteria on MT5, not because a scorecard says so. If your current broker passes, stay with it.
If you do want to try Axi, our introducing-broker code is 4592551. It costs you nothing and supports the research we publish here. Open an Axi Account →
Risk notice. Trading leveraged instruments carries a high risk of loss and is not suitable for everyone. Nothing in this article is financial advice, and no broker, spread, or execution figure described here is a guarantee of future performance or of profit. Test any setup on a demo account before risking capital.
AI Trade Lab is an Axi Introducing Broker (IB 4592551). We may receive compensation if you open an account through our links. This does not change what we publish or how we test.