Summary: MeTime is an opensource R package for reproducible analysis of longitudinal metabolomics data. It builds upona central S4 container, metime_analyser, that stores multiple datasets, associated metadata and analysis outputs, en-abling unified handling of complex longitudinal studies. Analyses are constructed by piping modular functions, beginningwith data transformations (mod_*), followed by calculations (calc_*), and optional meta-analysis (meta_*), so entireworkflows remain transparent and easy to modify. MeTime wraps numerous existing methods within a consistent inter-face, including sample and metabolite distributions, correlation/distance matrices, dimensionality reduction (PCA, UMAP,t-SNE), random forest imputation and feature selection via Boruta, eigenmetabolites and WGCNA-based clustering, con-servation index analysis, regression models (linear, mixed-effects, and generalized additive), and partial-correlation net-works. By retaining all intermediate results and provenance within the container, MeTime facilitates iterative explorationand ensures reproducible reporting via automatically generated HTML/PDF outputs. Comprehensive user guides, casestudies and reference documentation accompany the package, making MeTime a versatile platform for longitudinalomics workflows.