Digital Elevation Model 30m – the highest resolution topographic data generated from NASA’s Shuttle Radar Topography Mission (SRTM) was released globally by late 2015. The new DEM have been released with a 1 arc-second, or about 30 meters (98 feet), sampling that reveals the full resolution of the original measurements.
Here are the DEM Index:
The data format is TIFF file, and can be gennerated upto 10m interval contour line. Opencyclemap is a very good demo.