TreeTime is a Python-based framework for phylodynamic analysis, designed to estimate ancestral states, infer evolution models, reroot trees, and estimate molecular clock phylogenies and population size histories. It uses an approximate Maximum Likelihood approach, scaling linearly with dataset size, making it suitable for large-scale analyses of rapidly evolving viral pathogens. The tool can handle complex models, including time-reversible substitution models and relaxed clocks, and is implemented with efficient heuristics to optimize computational performance. TreeTime has been validated through simulations and real-world data, demonstrating its accuracy and robustness in various scenarios, including influenza and Ebola virus outbreaks. The software is available under an MIT license and can be accessed via a web interface or command-line scripts.TreeTime is a Python-based framework for phylodynamic analysis, designed to estimate ancestral states, infer evolution models, reroot trees, and estimate molecular clock phylogenies and population size histories. It uses an approximate Maximum Likelihood approach, scaling linearly with dataset size, making it suitable for large-scale analyses of rapidly evolving viral pathogens. The tool can handle complex models, including time-reversible substitution models and relaxed clocks, and is implemented with efficient heuristics to optimize computational performance. TreeTime has been validated through simulations and real-world data, demonstrating its accuracy and robustness in various scenarios, including influenza and Ebola virus outbreaks. The software is available under an MIT license and can be accessed via a web interface or command-line scripts.