marslab is an open-source suite of interoperable but loosely-coupled libraries and applications that facilitate rapid production of robust, stable, and flexible data analysis pipelines and workflows. It is principally designed for, but not restricted to, analysis of remote sensing multispectral data. It is in tactical use on the Mars 2020 mission for Mastcam-Z multispectral operations and has also been extensively applied to MSL Mastcam, M2020 Supercam, and MSL Chemcam data and tested with a wide variety of other multispectral data sets. It also serves as a core dependency to research domain infrastructure-level tools, like the Planetary Data Reader software. Many of its capabilities are fundamentally general-purpose; most could be easily modified for use with any number of spectral datasets. Its frameworks are specifically designed for flexible definition of instrument-specific behavior, production of extensible and reproducible data processing workflows, and use in tactical instrument operations.