  Fast Radio Bursts (FRBs) are recently discovered extra-galactic radio
transients which are now used as novel cosmological probes. We show how the
Bursts' Dispersion Measure can model-independently probe the history of
Hydrogen reionization. Using a FlexKnot free-form parameterization to
reconstruct the reionization history we predict an 11% accuracy constraint on
the CMB optical depth, and 4% accuracy on the midpoint of reionization, to be
achieved with 100 FRBs originating from redshifts z>5.
