Not quite as free (as in still under copyright), but you can download the ESV and HCSB at no cost and without DRM from the respective publishers.
The ESV is available from Crossway if you are willing to create an account at their online store. It can be downloaded as ePub and one of two different mobi files for Kindle:
ESV download page
The HCSB can be downloaded as an ePub from B&H Publishing Group without any signup:
HCSB ePub