Analyzing the nanocrystal (NC) size, morphology, and crystal structure is essential for understanding their fundamental properties. Here, we report NC-TEM Analyzer, a browser-assisted Python workflow for scale-calibrated transmission electron microscopy (TEM) image analysis of NCs. Demonstrated are scale-bar calibration, morphology-aware particle detection, spherical-dot diameter measurement, rotated-rectangle length, width, and aspect-ratio measurement for rod-like or platelet-like particles, and FFT-based lattice-spacing analysis from user-selected high-resolution TEM regions. Automatic candidates can be accepted, rejected, or geometrically corrected by the user, enabling human-in-the-loop validation. The software exports annotated images, histograms, summary statistics, CSV files, and structured metadata for reproducible comparison of nanocrystal samples.