apphash.io helps Cosmos SDK chain developers debug app hash mismatches (state non-determinism) by making application state divergence visible. When a mismatch happens, the chain halts, but finding where state diverged usually requires manual RPC diffing and log analysis. apphash.io shows which SDK module produced a different state root and the exact key-value differences inside that module across nodes, turning blind debugging into a concrete, inspectable problem.