This is the list of deals in the Microsoft Freecell / Freecell Pro first 8 giga deals that were not known whether they are solvable or not with 4 freecells.
For more information, see:
These deals have later been determined to be solvable or not - see https://github.com/shlomif/freecell-pro-impossible-deals and http://fc-solve.shlomifish.org/charts/fc-pro--4fc-deals-solvability--report/ .
License is the MIT/Expat license.