Ke4 measurements with NA48/NA62

The NA48/2 collaboration has analysed more than one million K±→π+π−e±ν decays, resulting in the improved determination of branching fraction by a factor of 3 and high precision form factor measurements. Concurrently, about 45000 K±→π0π0e±ν decays have been analyzed. Background contamination below the percent level and very good π0 reconstruction allow the first accurate measurement of the branching fraction and decay form factor at the percent level. The achieved precision makes possible the observation of small effects such as π+π−→π0π0 re-scattering. Both Ke4 modes decay properties bring new precise inputs to Low Energy QCD studies and can provide strong tests of ChPT predictions. Future prospects include the observation of several thousand decays in similar muonic modes K±→π0π0μ±ν and K±→π+π−μ±ν, that could be studied also in the forthcoming NA62 experiment.