Quick answer
OANDA is simplest (bearer token, practice host, 120 req/s, up to 5,000 candles per call). IG needs an API key plus a login session and limits history to 10,000 points a week, but adds CFDs and spread bets. Saxo uses OAuth and covers the most asset classes, with a 24-hour developer token for simulation.
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 |
Which one should you pick?
OANDA if you want pure FX with minimal setup.
Build with OANDAIG if you want CFDs or spread betting.
Build with IGSaxo OpenAPI if you want one account for FX, stocks and derivatives.
Build with Saxo OpenAPI
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.