Checking History Determinism for Parity Automata Is in NP

History-deterministic automata, often also called good-for-games, are an intermediate model between deterministic and nondeterministic automata, which are particularly well-suited for applications in verification and reactive synthesis. We show that deciding whether a parity automaton is history-deterministic is in NP. Our result matches an NP-hardness lower bound (Prakash 2024) and builds on insights from a fixed-parameter tractable algorithm (Lehtinen and Prakash 2025). This settles the complexity of the problem, which has been open since 2006.