We present spaxel-by-spaxel stellar population fits for the ~10 000 MaNGA data cubes. We provide multiple extension fits files, nominated as MEGACUBES, with maps of several properties as well as emission-line profiles that are provided for each spaxel. All the MEGACUBES are available through a web interface (https://manga.linea.org.br/ or http://www.if.ufrgs.br/~riffel/software/megacubes/). We also defined a final Active Galactic Nuclei (AGN) sample, as well as a control sample matching the AGN host galaxy properties. We have analysed the stellar populations and spatially resolved emission-line diagnostic diagrams of these AGNs and compared them with the control galaxies sample. We find that the relative fractions of young (t ≤56 Myr) and intermediate-age (100 Myr ≤t ≤ 2 Gyr) show predominantly a positive gradient for both AGNs and controls. The relative fraction of intermediate-age stellar population is higher in AGN hosts when compared to the control sample, and this difference becomes larger for higher [O III] luminosity AGNs. We attribute this to the fact that extra gas is available in these more luminous sources and that it most likely originates from mass-loss from the intermediate-age stars. The spatially resolved diagnostic diagrams reveal that the AGN emission is concentrated in the inner 0.5 Re (effective radius) region of the galaxies, showing that the AGN classification is aperture dependent and that emission-line ratios have to be taken together with the H α equivalent width for proper activity classification. We present a composite 'BPT+WHAN' diagram that produces a more comprehensive mapping of the gas excitation.