Introduction: How Should You Choose the "Eyes" of Your Trading Strategy? In 2026, with the widespread adoption of AI trading agents and quantitative strategies, the role of financial data APIs has fundamentally changed. They are no longer just "data carriers" but have become the "eyes" of trading strategies. There's a set of numbers that should alert every developer—nearly 68% of strategy developers encountered obstacles in R&D when building forex analysis and trading systems due to misjudging API real-time performance metrics, with 35% experiencing deviations between backtesting and live trading exceeding 15% . This means that no matter how rigorous your algorithmic models are or how deep your factor mining goes, everything is futile without high-quality data infrastructure support. The forex market sees daily trading volumes exceeding $6 trillion, with major currency pairs like EUR/USD and GBP/USD potentially experiencing dramatic fluctuations every second.…