Rapid processes including both inorganic and organic precipitation at high supersaturation require homogenous micromixing. A multi-inlet vortex mixer (MIVM) was explored in terms of its ability to deliver rapid micromixing and flexibility. Confined impinging jet mixers (CIJM) have two coaxial jets which collide and, therefore, require equal inlet momenta and stream flow rates. In contrast, the MIVM allows the ratio of organic and inorganic phase can be changed freely and multiple compounds could be loaded in different inlet streams. This offers advantages for the production of organic nanoparticles. The organic solvent volumes used can be reduced, which increases supersaturation and the stability of the nanoparticles by depressing the Ostwald ripening rate. Nanoparticles with multipule active compounds can be easily generated. Parallel competition reactions (“Bourne reactions”) were employed as a “chemical ruler” to characterize the mixing time of the MIVM. The acid hydrolysis of 2,2-dimethoxypropane (DMP) for a wide range of Reynolds numbers has been measured experimentally and compared with the numerical simulation data. The computational fluid dynamics (CFD) model for turbulent reacting flow is based on solving the composition probability density function (PDF) transport equation using the direct-quadrature-method-of-moments (DQMOM). The conditional molecular diffusion term is closed with the interaction-by-exchange-with-the-mean (IEM) model. The numerical simulation, with no adjustable parameters, predicts experimental data well and provides a wealth of detailed information on the reacting flow inside of the MIVM. Both experimental and numerical results show a clear transition from low Reynolds number laminar flow to high Reynolds number, turbulence-like flow. Different arrangements of the inlet streams of the MIVM were compared to optimize the operation condition. The characteristic mixing time of the MIVM is in the range of milliseconds.