This derived product set consists of Global Navigation Satellite System Ionosphere Vertical Total Electron Content (VTEC) comparison product (daily files) from the NASA Crustal Dynamics Data Information System (CDDIS). GNSS provide autonomous geo-spatial positioning with global coverage. GNSS data sets from ground receivers at the CDDIS consist primarily of the data from the U.S. Global Positioning System (GPS) and the Russian GLObal NAvigation Satellite System (GLONASS). Since 2011, the CDDIS GNSS archive includes data from other GNSS (Europe’s Galileo, China’s Beidou, Japan’s Quasi-Zenith Satellite System/QZSS, the Indian Regional Navigation Satellite System/IRNSS, and worldwide Satellite Based Augmentation Systems/SBASs), which are similar to the U.S. GPS in terms of the satellite constellation, orbits, and signal structure. GNSS observations from a global network can be utilized for atmospheric measurements. Analysis Centers (ACs) of the International GNSS Service (IGS) retrieve GNSS data on regular schedules to produce independently computed VTEC maps. The IGS Ionosphere Analysis Center Coordinator (ACC) uses these individual AC solutions to generate the official IGS VTEC maps. The validation products are used to compare the IGS and AC solutions of generated VTEC maps. There are three types of ionosphere product evaluation/validation products: 1) the upcwWWWW.YYv.Z files provide an evaluation of the final weekly combination solution of VTEC maps with the individual analysis center contributions; 2) the gpsgDDD0.YYi.Z files are provided by the Center for Orbit Determinate (CODE) at the Astronomical Institute at the University of Bern (AIUB) Switzerland; these files contain GPS broadcast ionosphere model for day YYDDD; and 3) the ckmgDDD0.YYi.Z products are computed by CODE using their Klobuchar model, best fitting CODE’s final ionosphere solution, also available from the CDDIS.