This paper presents a novel lens-free on-chip tomography (LFOCT) technique, termed wavelength-scanning Fourier ptychographic diffraction tomography (wsFPDT), which enables high-throughput, motion-free, label-free 3D tomography with quasi-uniform imaging resolution across the full field-of-view (FOV). Unlike traditional methods that rely on angularly-variable illuminations, wsFPDT uses on-axis wavelength-variable illuminations ranging from 430 to 1200 nm. The corresponding under-sampled diffraction patterns are processed using an iterative ptychographic reconstruction algorithm to recover the pixel-super-resolved 3D refractive index (RI) distribution of the sample. This approach eliminates the need for mechanical motion during image acquisition and ensures quasi-uniform, high-resolution imaging across the entire FOV. The effectiveness of wsFPDT is demonstrated through high-throughput, billion-voxel 3D tomographic imaging results with a lateral resolution of 775 nm and an axial resolution of 5.43 μm over a large FOV of 29.85 mm² and an imaging depth of >200 μm. The method is validated by imaging various samples, including micro-polystyrene beads, diatoms, and mouse mononuclear macrophage cells, revealing quantitative morphological properties such as area, volume, and sphericity index. The wsFPDT technique offers a powerful tool for high-throughput biological applications, particularly in label-free and quantitative 3D imaging of biological samples.This paper presents a novel lens-free on-chip tomography (LFOCT) technique, termed wavelength-scanning Fourier ptychographic diffraction tomography (wsFPDT), which enables high-throughput, motion-free, label-free 3D tomography with quasi-uniform imaging resolution across the full field-of-view (FOV). Unlike traditional methods that rely on angularly-variable illuminations, wsFPDT uses on-axis wavelength-variable illuminations ranging from 430 to 1200 nm. The corresponding under-sampled diffraction patterns are processed using an iterative ptychographic reconstruction algorithm to recover the pixel-super-resolved 3D refractive index (RI) distribution of the sample. This approach eliminates the need for mechanical motion during image acquisition and ensures quasi-uniform, high-resolution imaging across the entire FOV. The effectiveness of wsFPDT is demonstrated through high-throughput, billion-voxel 3D tomographic imaging results with a lateral resolution of 775 nm and an axial resolution of 5.43 μm over a large FOV of 29.85 mm² and an imaging depth of >200 μm. The method is validated by imaging various samples, including micro-polystyrene beads, diatoms, and mouse mononuclear macrophage cells, revealing quantitative morphological properties such as area, volume, and sphericity index. The wsFPDT technique offers a powerful tool for high-throughput biological applications, particularly in label-free and quantitative 3D imaging of biological samples.