  We study the heavy-light mesons within basis light-front quantization. The
resulting mass spectra of $D$, $D_s$, $B$, and $B_s$ agree reasonably well with
experiments. We also predict states which could be measured in the near future.
In the light-front formalism, we calculate the light-front wave functions and
additional experimental observables, such as parton distribution functions,
distribution amplitudes, and decay constants by means of integrations over
light-front wave functions. We also provide ratios of decay constants for
selected pseudoscalar meson decays ($D_s$ to $D$ and $B_s$ to $B$) as they may
prove to be theoretically more robust and more reliably determined in
experiments. We find that our ratios are systematically smaller than existing
experiment and other approaches by $5-18\%$.
