The Galileo High Accuracy Service (HAS) offers free, real-time Precise Point Positioning (PPP) corrections via Galileo (E6-B) and Internet, supporting Galileo (E1, E5a, E5b, E6) and GPS (L1, L5) signals. HAS provides SSR orbit, clock corrections, and biases, achieving decimeter-level accuracy (20cm horizontal, 40cm vertical) within 300 seconds, per the HAS ICD. This study compares HAS products with other analysis centers, verifying declared accuracy. Using a Septentrio Mosaic X5 GNSS receiver, real-time HAS data was collected over three weeks, verified against CODE products, and assessed for PPP performance under various scenarios to evaluate HAS reliability for high-accuracy positioning.