Nonlixis is a sleek optical calculator designed to simplify nonlinear crystal analysis by providing quick estimates of phase-matching angles and conversion efficiencies for SHG, OPO, and parametric amplification processes. With an intuitive interface, colorful design, and easy parameter input for pump wavelength, crystal length, birefringence, and temperature, it delivers instant insights that support research, education, and early-stage design decisions without requiring complex simulations.