Arena is a free chess graphical user interface for Windows developed by Martin Blume, widely used for running engine vs. engine matches, analyzing games with multiple engines simultaneously, and general engine-based analysis. The software supports both UCI and WinBoard/XBoard engine protocols, making it compatible with virtually every chess engine available.

Beyond standard analysis, Arena is particularly strong for engine tournament setup: players can configure engine competitions with customizable time controls, starting positions, opening books, and logging. The interface allows side-by-side engine comparisons and has been used extensively in the computer chess community for testing engine performance.

Arena is completely free for personal use and supports hundreds of freely downloadable engines. It is primarily a Windows application, though it can run on other platforms via Wine. For players building a desktop analysis setup, Arena paired with Stockfish and other engines is one of the most powerful free configurations available.