Quick answer
OANDA’s v20 REST API is the simplest forex broker API: one bearer token, a free practice host and 120 requests per second. IG adds CFDs and spread betting with a REST API and demo account; Saxo covers FX plus equities and derivatives via OAuth; cTrader Open API works across many cTrader brokers; Interactive Brokers has the lowest spreads at scale but needs a gateway.
Side-by-side comparison
| API | Markets | Auth | Paper / sandbox | Pricing | In AlgoGP |
|---|---|---|---|---|---|
| OANDA | Forex, CFDs, Indices | REST + API key | Free demo (fxPractice) account | Free API with an account | Built into AlgoGPPro |
| IG | Forex, CFDs, Indices, Stocks, Options | REST + API key | Demo account (demo-api.ig.com) | API free; 10k historical points/week | Guide |
| Saxo OpenAPI | Stocks, ETFs, Options, Futures, Forex, CFDs, Bonds | OAuth login | Simulation environment; 24-hour developer token | API free; non-FX market data needs entitlements | Guide |
| cTrader Open API | Forex, CFDs, Indices, Crypto | Local gateway | Demo environment with demo accounts | API free; broker spreads/commissions apply | Guide |
| Interactive Brokers | Stocks, ETFs, Options, Futures, Forex, Bonds, Crypto | Local gateway | Paper trading account (TWS port 7497, Gateway 4002) | API free with account; market data subscriptions extra | Guide |
Which one should you pick?
OANDA if you want the quickest working forex bot with a practice account.
Build with OANDAIG if you are in the UK, EU or Australia and want CFDs too.
Build with IGSaxo OpenAPI if you need FX alongside equities and options outside the US.
Build with Saxo OpenAPIcTrader Open API if your broker of choice offers cTrader.
Build with cTrader Open API
Frequently asked questions
Which forex brokers have a REST API?
OANDA, IG and Saxo offer REST; cTrader Open API uses TCP/WebSocket messages; IBKR uses a gateway.
Test the strategy before you pick the API
Describe your idea to AlgoGP’s copilot, backtest it on years of stock, crypto or forex data with realistic costs, then export Python wired to OANDA or any built-in broker. Swap the broker later without touching the strategy.
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AlgoGP is not affiliated with any provider listed. Details change; check each provider’s documentation. Nothing here is investment advice.