The operational concept of Splines is centered around interpolation between up to 16 user-configured nodes mapped across an X-axis (time) and a Y-axis (voltage). Users manipulate the curve path between these points using dedicated Tension, Continuity, and Bias parameters. The resulting shapes are output as continuous CV or audio waveforms.

Operating across a frequency range from 0.001 Hz to 20 kHz, Splines handles several distinct synthesis and modulation tasks. At low frequencies, it functions as a looping LFO, an envelope generator, or a step sequencer with per-node trigger, gate, and probability options. In the audio range, the module operates as a wavetable oscillator with digital waveshaping tools, including folding, wrapping, rectification, and bitcrushing. An integrated Level control and dedicated CV input allow the module to function as a standalone VCA.

The visual interface utilizes a 1.83" color LCD screen to display the curve layout, active parameters, and incoming modulation data. The module provides six CV inputs, each featuring its own mini-oscilloscope visualization on the screen. The built-in quantizer supports microtonal scales via Scala (.scl) files, which are transferred directly to the module's internal storage via a front-panel USB-C port. This USB connection also manages firmware updates, preset management, and data backups.