We present highlights from the end-to-end testing and integration of the Colorado Ultraviolet Transit Experiment (CUTE), a NASA-funded 6U CubeSat designed to study the atmospheric composition and escape rates of short-period (P = 1-5 days) exoplanets. The CUTE science payload is comprised of a long-slit NUV spectrograph (R ~ 2000, 250–330 nm), fed by a rectangular (8 x 20 cm) Cassegrain telescope, together filling 4U of the spacecraft’s volume. We focus on CUTE’s end-to-end performance and process by providing a full-field performance map, a wavelength solution, and a description of the suite of custom test facilities employed to produce them. CUTE is scheduled to launch with the Landsat 9 mission in late 2021. Once in orbit, CUTE will observe ~ 6-10 transits of more than 10 extreme exoplanets. We conclude by placing the CUTE mission in the context of current and future exoplanet missions by projecting its expected on-orbit performance into the potential impact CUTE will have on exoplanet atmospheric science.