  We present the first determination of the Hubble constant $H_0$ from strong
lensing time delay data and type Ia supernova luminosity distances that is
independent of the cosmological model. We also determine the spatial curvature
model-independently. We assume that light propagation over long distances is
described by the FLRW metric and geometrical optics holds, but make no
assumption about the contents of the Universe or the theory of gravity on
cosmological scales. We find $H_0=75.7^{+4.5}_{-4.4}$ km/s/Mpc and
$\Omega_{K0}=0.12^{+0.27}_{-0.25}$. This is a 6\% determination of $H_0$. A
weak prior from the cosmic microwave background on the distance to the last
scattering surface improves this to $H_0=76.8^{+4.2}_{-3.8}$ km/s/Mpc and
$\Omega_{K0}=0.18^{+0.25}_{-0.18}$. Assuming zero spatial curvature, we get
$H_0=74.2^{+3.0}_{-2.9}$ km/s/Mpc, a precision of $4\%$. The measurements also
provide a consistency test of the FLRW metric: we find no evidence against it.
