Rapidly discovered comets are often known only from their orbital elements and a handful of early images, creating a need for tools that can interpret dust tail morphology quickly. This work presents a browser based, real time, three dimensional simulator of cometary dust tails. Dust particles are propagated under solar gravity reduced by radiation pressure, following the Finson--Probstein approach, with the parameter \(\beta\) capturing the dependence on grain size and density. Using WebGPU compute shaders, the simulator propagates and renders up to \(3\times10^{6}\) particles interactively in a web browser. The simulator was validated in three stages. First, the internal Keplerian orbit propagation was compared against an independent two body propagator for elliptic (67P/Churyumov--Gerasimenko), synthetic parabolic, and hyperbolic (3I/ATLAS) cases, giving meter-level agreement. Second, synthetic sky plane projections were compared with Zwicky Transient Facility observations of 67P/Churyumov--Gerasimenko, C/2022 E3 (ZTF) and C/2017 K2 (PANSTARRS) across fourteen epochs, where the simulated isophotes reproduced the observed tail direction, width and extent with Jaccard indices of 0.57--0.82 without a registration tolerance and 0.63--0.83 with one. Third, the three dimensional dust density distribution was compared with the established COMTAILS code for 67P; truncating the reference grain population at the simulator's \(\beta \le 1\) limit brings the two into agreement at the Monte Carlo sampling level, showing that the residual arises from the grain size domain rather than from the GPU propagation.