The web-based application Blast helps astronomers understand the connection between transient events, such as supernovae, and the galaxies in which they live. This program will expand the capabilities of Blast to match the challenges created by the vast amount of data that will be generated by the new generation of telescopes, such as Rubin (NSF-DOE) and Roman (NASA). This program will also work with Zooniverse, a citizen science platform with more than 2.7 million registered users. With Zooniverse this program will engage the public in a variety of research projects related to transients and their host galaxies. Over the last several years, the wealth of transient data has increased dramatically and with it, the discovery potential. This program focuses on the ways in which the physics of astrophysical transients are fundamentally linked with the properties of the host galaxies in which their progenitor stars form and evolve. Understanding the stellar populations that give rise to these transients plays a key role in our understanding of the transients themselves, including constraining the progenitor systems of core-collapse supernovae, correcting Type Ia supernova distances, and probabilistically classifying transients with galaxy data. This program will support a major upgrade to Blast, a web application for host-galaxy inference, which provides real-time spectral energy distribution fitting from ultraviolet to infrared wavelengths for every astrophysical tra