UTM vs Web Mercator

Compare the Web Mercator tile grid (always axis-aligned to lat/lng) with the UTM grid (axis-aligned to each zone's Transverse Mercator projection). Zoom in to see the UTM grid subdivide and diverge from the Mercator grid, especially at higher latitudes.

About these coordinate systems

Web Mercator is a single global projection used by virtually all web maps. Its tile grid is always aligned to geographic north (latitude/longitude axes).
UTM (Universal Transverse Mercator) is a coordinate system that divides the world into 60 zones of 6° longitude each. Each zone uses its own Transverse Mercator projection centered on its central meridian.
Grid north equals true north only along a zone's central meridian. The convergence angle grows with distance from center and with latitude: γ ≈ Δλ · sin(φ).