GrADSAT: A parallel sat solver for the grid. We present GrADSAT, a parallel satisfiability solver aimed at solving hard SAT instances using a large number of widely distributed commodity computational resources. The GrADSAT parallel algorithm uses intelligent backtracking, sharing of learned clauses and clause reduction. The distributed implementation allows for dynamic resource acquisition. We show how the large number of computational resources and communication overhead influence the implementation strategy. GrADSAT is compared against the best sequential solver using a wide variety of problem instances. The results show that GrADSAT delivers speed-up on most instances. Furthermore it is capable of solving problem instance which were never solved before.