miauu's Quick Spline Measure is a 3ds Max tool from developer miauu for measuring spline geometry. It reports the lengths of the snapped segment and its closest adjacent segment, the distance between the points of those two segments, and the angle between them. All of this happens without selecting any spline.
Every measurement can be copied to the clipboard at any time, so the values are available to use elsewhere. The tool covers Autodesk 3ds Max and 3ds Max Design releases from 2017 through 2026, with the developer's requirements listing versions up to 2027. Version 1.02 was last updated on 2025-06-16.
Described by its developer as a commercial tool, it is listed as free in this catalog. A demo video is available, and the developer's page carries additional information about the tool and its current licensing.