eN-LNP is a fully automated, standalone microfluidic high-throughput platform designed to rapidly screen lipid nanoparticle (LNP) synthesis conditions and characterize key properties such as particle size, polydispersity index (PDI), and composition. Built around a standard 96-well format with an integrated microfluidic mixer, the system enables substantially higher throughput while offering precise and tunable mixing control through adjustable inlet number, position, diameter, and individual flow regulation. Its pressure-driven flow system supports a broad operating range, from microliter-scale screening to larger-volume production, allowing flexibility across diverse experimental conditions. The platform is built using optimized 3D-printing methods to produce low-cost, chemically and mechanically robust microfluidic devices compatible with a wide range of solvents used in biopharmaceutical applications. In addition, the HT synthesis device can be integrated with inline solvent separation and modification modules, enabling direct characterization using analytical tools such as DLS, UV/Vis, and IR plate readers. Coupled with an easy-to-use graphical user interface, eN-LNP provides a scalable and reliable solution for rapid LNP formulation development and process optimization.